The amino acid sequence of the alpha subunit of mouse salivary androgen-binding protein (ABP), with a comparison to the partial sequence of the beta subunit and to other ligand-binding proteins

It has been suggested that three distinct genes,Abpa, Abpb, andAbpg, determine the three subunits of mouse salivary androgen-binding protein (ABP) (Dlouhy, S. R.,et al., Genetics 115, 535, 1987). We report the putative amino acid sequence of the subunit common to all forms of ABP, the Alpha subunit, and the partial amino acid sequence of the Beta subunit. These sequences have little in common, supporting the notion of at least two distinct genes coding for the subunits of the most common form of salivary ABP, the A:B dimer. A search of GenBank showed that these sequences have not been reported previously. The Beta subunit shows significant homology with helospectin, a member of the glucagon superfamily, but not enough homology to assign it to the family. No homology exists between ABP subunits and members of the ligand-binding carrier family of proteins nor does ABP show homology with other androgen-binding proteins. Particularly interesting is the observation that there is no relationship to rat prostatic steroid binding protein (PBP), given the similarities in protein tertiary structure, the numbers of subunits and their genes, and the earlier observation of ABP cross-reactive material in mouse prostate.Partial support for this work was provided by a PHS AREA award and by the Butler Academic Grants program. Both sources of support are greatly appreciated.A portion of this work constituted partial fulfillment of the honors thesis requirement for Butler University.     

The mouse salivary androgen-binding protein (ABP) alpha subunit closely resembles chain 1 of the cat allergen Fel dI

Androgen-binding protein (ABP) is found in the salivas of a wide variety of rodents and it has been proposed that ABP functions in sex and/or subspecies recognition (Karn and Dlouhy,J. Hered. 82, 453, 1991). This is a report of significant identity between the alpha subunit of mouse salivary ABP and Chain 1 of cat allergen Fel dI (50% identity), as well as with two other proteins that share identity with Chain 1 of Fel dI, rabbit uteroglobin (27% identity with ABP alpha) and human lung Clara 10 (27% identity with ABP alpha). The secondary structure predicted for the mouse ABP alpha subunit is a very good fit with the secondary structure determined by X-ray crystallography for rabbit uteroglobin, a protein that shares with mouse ABP the capability of binding steroid. Fel dI is found in cat saliva, sebaceous glands, and pelt. Its function is not known but it has been proposed to be involved in protecting dry epithelia, a parallel to uteroglobin protecting wet epithelia. Since mice, like cats, lick themselves and each other extensively, coating their pelts with ABP may be part of this or another biological function.     

ASSOCIATIONS OF BETA NERVE GROWTH FACTOR WITH BOVINE SERUM ALBUMIN AS WELL AS WITH THE ALPHA AND GAMMA SUBUNITS OF THE 7S MACROMOLECULE1

Abstract— The association of ¹²⁵ I-diiodo-Beta nerve growth factor with bovine serum albumin (BSA), as well as with the Gamma and Alpha subunits of the 7S nerve-growth factor (NGF) macromolecule are described. In the absence of added protein, the stable thermodynamic state for Beta (pH 7.4) at concentrations below 10^?7 M is absorbed to the walls of the reaction vessel. Above 10^?7 M the sites on the wall of the reaction vessel begin to saturate, and Beta is found free in solution. Addition of other soluble proteins to the system (i.e. BSA, Alpha and Gamma) causes a displacement of the Beta from the walls of the reaction vessel. This displacement is the result of the binding of the Beta to the added soluble protein. The binding of Beta to BSA is a complex function of BSA concentration, suggesting multiple sets of sites and/or cooperative interactions. In contrast, the characteristics of the association of Beta with Gamma and Alpha indicate an interaction between discrete sets of sites on the respective polypeptide chains. The Beta-Gama association is a bimolecular association with an apparent first thermodynamic association constant of 6.25 × 10⁵M^?1. The association between Beta and Alpha is also bimolecular and has an apparent first thermodynamic association constant of 2.0 × 10⁵M^?1. In addition, dissociation studies suggest that the Gamma-Beta complex binds Alpha with a substantially higher affinity than does Beta or Gamma alone. These data strongly support the conclusion that there is a unique biologically determined relationship among these polypeptides. The data are discussed with respect to the experimental use of Beta NGF. A new operational paradigm for the controlled use of the Beta NGF is presented. This approach is based on the use of a thermodynamically stabilized 7S complex and the analysis of relative apparent affinities.     

Characterization of two forms of mouse salivary androgen-binding protein (ABP): implications for evolutionary relationships and ligand-binding function

Mouse salivary androgen-binding protein (ABP) is a member of the secretoglobin family produced in the submaxillary glands of house mice (Mus musculus). We report the cDNA sequences and amino acid sequences of the beta and gamma subunits of ABP from a mouse cDNA library, identifying the two subunits by their pIs and molecular weights. An anomalously high molecular weight of the alpha subunit is likely due to glycosylation at a single site. A phylogenetic comparison of the three subunits of ABP with the chains of other mammalian secretoglobins shows that ABP is most closely related to mouse lachrymal protein and to the major cat allergen Fel dI. An evaluation of the most conserved residues in ABP and the other secretoglobins, in light of structural data reported by others [Callebaut, I., Poupon, A., Bally, R., Demaret, J.-P., Housset, D., Delettre, J., Hossenlopp, P., and Mornon, J.-P. (2000) Ann. N.Y. Acad. Sci. 923, 90-112; Pattabiraman, N., Matthews, J., Ward, K., Mantile-Selvaggi, G., Miele, L., and Mukherjee, A. (2000) Ann. N.Y. Acad. Sci. 923, 113-127], allows us to draw conclusions about the critical residues important in ligand binding by the two different ABP dimers and to assess the importance of ligand binding in the function of the molecule. In addition to the cDNAs, which represent those of the musculus subspecies of Mus musculus, we also report the coding regions of the beta and gamma subunit cDNAs from two other mouse inbred strains which represent the other two subspecies: M. musculus domesticus and M. musculus castaneus. The high nonsynonymous/synonymous substitution rate ratios (K(a)/K(s)) for both the beta and gamma subunits suggest that these two proteins are evolving under strong directional selection, as has been reported for the alpha subunit [Hwang, J., Hofstetter, J., Bonhomme, F., and Karn, R. (1997) J. Hered. 88, 93-97; Karn, R., and Clements, M. (1999) Biochem. Genet. 37, 187-199].     

Congenic strain analysis reveals genes that are rapidly evolving components of a prezygotic isolation mechanism mediating incipient reinforcement

Two decades ago, we developed a congenic strain of Mus musculus, called b-congenic, by replacing the androgen-binding protein Abpa27(a) allele in the C3H/HeJ genome with the Abpa27(b) allele from DBA/2J. We and other researchers used this b-congenic strain and its C3H counterpart, the a-congenic strain, to test the hypothesis that, given the choice between signals from two strains with different a27 alleles on the same genetic background, test subjects would prefer the homosubspecific one. It was our purpose in undertaking this study to characterize the segment transferred from DBA to the C3H background in producing the b-congenic strain on which a role for ABPA27 in behavior has been predicated. We determined the size of the chromosome 7 segment transferred from DBA and the genes it contains that might influence preference. We found that the "functional" DBA segment is about 1% the size of the mouse haploid genome and contains at least 29 genes expressed in salivary glands, however, only three of these encode proteins identified in the mouse salivary proteome. At least two of the three genes Abpa27, Abpbg26 and Abpbg27 encoding the subunits of androgen-binding protein ABP dimers evolved under positive selection and the third one may have also. In the sense that they are subunits of the same two functional entities, the ABP dimers, we propose that their evolutionary histories might not be independent of each other.     

Female preference for male saliva: implications for sexual isolation of Mus musculus subspecies

We studied the effects of a single genetic change on a complex mammalian behavior using animals congenic for two variants of Abpa, the gene for the alpha subunit of mouse salivary androgen-binding protein (ABP), in two-way preference tests. Females exhibited a preference for investigating salivas of males of their own genetic type of ABP but not for urines of either type of male. This preference behavior is consistent for samples of mice from geographically diverse populations of Mus musculus domesticus and M. m. musculus. These findings provide an explanation for the observation that this gene is evolving under strong selection.     

Production of an antibody to mouse salivary androgen binding protein (ABP) and its use in identifying a prostate protein produced by a gene distinct from Abp

We previously demonstrated polymorphism of a mouse salivary protein which, because of its ability to bind androgen, we designated androgen binding protein (ABP) and its structural gene, Androgen binding protein (Abp). This report describes the purification of salivary ABP and presents the amino acid composition of its subunits. Using an antibody raised against the purified protein, we demonstrated the presence of cross-reactive material (CRM) in mouse parotid, submaxillary, sublingual, and prostate glands by double immunodiffusion. Immunohistochemical detection of proteins on electroblots of polyacrylamide electrophoresis and isoelectric focusing gels, however shows that the prostate CRM is a protein with electrophoretic and isoelectric focusing behavior distinct from that of salivary ABP isoproteins. Because the DBA/2J strain has a variant of salivary ABP, that strain was analyzed to determine if a prostate ABP-CRM variant was present. The approach was hampered by an inability to detect CRM in the prostates of DBA/2J mice. Prostate CRM was detected, however, in some progeny from repeated backcrosses of DBA/2J X C3H/St hybrids to the C3H/St and DBA/2J parental strains. The prostate CRM detected in samples from animals heterozygous for salivary Abp appears to be identical to C3H/St prostate CRM, suggesting that the gene controlling prostate ABP-CRM is related to, but distinct from, Abp. The reason for reduced or absent CRM in the prostates of DBA/2J males is unknown but this finding suggests that there are strain-related differences in the expression of this prostate protein.     

Testing for selection on the androgen-binding protein in the Danish mouse hybrid zone

The three peripheral subspecies of the house mouse Mus musculus have fixed specific variants of the androgen-binding protein (ABP) that have been proposed to be part of a recognition mechanism that could participate in sexual isolation between the subspecies. We tested for selection on Abpa by characterizing the pattern of Abpa introgression across a transect of the hybrid zone between M. m. musculus and M. m. domesticus in Jutland. On the musculus side, the cline for Abpa resembled that of a nearly neutral allozyme more than that of strongly selected X and Y chromosome markers. However, the high central step which displaces the tail of introgression of Abpa to higher frequencies was best accounted for by linkage to a locus under strong selection against hybrids. Still, we cannot exclude that this pattern results from weak selection against Abpa in the tail of introgression, which would be compatible with an assortative choice mechanism. On the domesticus side there was little introgression close to the hybrid zone, presumably due to a geographical barrier to migration. However, substantial frequencies of musculus alleles occurred further away, suggesting mixed colonization patterns as well as flow across the hybrid zone.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 447–459.     

The complex history of a gene proposed to participate in a sexual isolation mechanism in house mice

Previous behavioral experiments showed that mouse salivary androgen-binding protein (ABP) was involved in interindividual recognition and might play a role in sexual isolation between house mouse (Mus musculus) subspecies. The pattern of evolution of Abpa, the gene for the alpha subunit of ABP, was found to be consistent with this hypothesis. Abpa apparently diverged rapidly between species and subspecies with a large excess of nonsynonymous substitutions, a lack of exon polymorphism within each of the three subspecies, and a lack of intron polymorphism in the one subspecies studied (M. musculus domesticus). Here we characterized the intron and exon sequence variations of this gene in house mouse populations from central Eurasia, a region yet unsampled and thought to be close to the cradle of the radiation of the subspecies. We also determined the intron and exon sequences in seven other species of the genus Mus. We confirmed the general pattern of rapid evolution by essentially nonsynonymous substitutions, both inter- and intraspecifically, supporting the idea that Darwinian selection has driven the evolution of this gene. We also observed a uniform intron sequence in five samples of M. musculus musculus, suggesting that a selective sweep might have occurred for that allele. In contrast to previous results, however, we found extensive intron and exon polymorphism in some house mouse populations from central Eurasia. We also found evidence for secondary admixture of the subspecies-specific alleles in regions of transition between the subspecies in central Eurasia. Furthermore, an abnormal intron phylogeny suggested that interspecific exchanges had occurred between the house mouse subspecies and three other Palearctic species. These observations appear to be at variance with the simple hypothesis that Abpa is involved in reproductive isolation. Although we do not rule out a role in recognition, the situation appears to be more complex than previously thought. Thus the selective mechanism behind the evolution of Abpa remains to be resolved, and we suggest that it may have changed during the recent colonization history of the house mouse.     

Hetero-bivalent nanobodies provide broad-spectrum protection against SARS-CoV-2 variants of concern including Omicron

SARS-CoV-2 variants with adaptive mutations have continued to emerge, causing fresh waves of infection even amongst vaccinated population. The development of broad-spectrum antivirals is thus urgently needed. We previously developed two hetero-bivalent nanobodies (Nbs), aRBD-2-5 and aRBD-2-7, with potent neutralization activity against the wild-type (WT) Wuhan isolated SARS-CoV-2, by fusing aRBD-2 with aRBD-5 and aRBD-7, respectively. Here, we resolved the crystal structures of these Nbs in complex with the receptor-binding domain (RBD) of the spike protein, and found that aRBD-2 contacts with highly-conserved RBD residues and retains binding to the RBD of the Alpha, Beta, Gamma, Delta, Delta plus, Kappa, Lambda, Omicron BA.1, and BA.2 variants. In contrast, aRBD-5 and aRBD-7 bind to less-conserved RBD epitopes non-overlapping with the epitope of aRBD-2, and do not show apparent binding to the RBD of some variants. However, when fused with aRBD-2, they effectively enhance the overall binding affinity. Consistently, aRBD-2-5-Fc and aRBD-2-7-Fc potently neutralized all of the tested authentic or pseudotyped viruses, including WT, Alpha, Beta, Gamma, Delta, and Omicron BA.1, BA.1.1 and BA.2. Furthermore, aRBD-2-5-Fc provided prophylactic protection against the WT and mouse-adapted SARS-CoV-2 in mice, and conferred protection against the Omicron BA.1 variant in hamsters prophylactically and therapeutically, indicating that aRBD-2-5-Fc could potentially benefit the prevention and treatment of COVID-19 caused by the emerging variants of concern. Our strategy provides new solutions in the development of broad-spectrum therapeutic antibodies for COVID-19.Subject terms: X-ray crystallography, Innate immunity     

Reduced nucleotide variability at an androgen-binding protein locus (Abpa) in house mice: evidence for positive natural selection.

Previous work has shown that the gene for the alpha subunit of androgen-binding protein, Abpa, may be involved in premating isolation between different subspecies of the house mouse, Mus musculus. We investigated patterns of DNA sequence variation at Abpa within and between species of mice to test several predictions of a model of neutral molecular evolution. Intraspecific variation among 10 Mus musculus domesticus alleles was compared with divergence between M. m. domesticus and M. caroli for Abpa and two X-linked genes, Glra2 and Amg. No variation was observed at Abpa within M. m. domesticus. The ratio of polymorphism to divergence was significantly lower at Abpa than at Glra2 and Amg, despite the fact that all three genes experience similar rates of recombination. Interspecific comparisons among M. m. domesticus, Mus musculus musculus, Mus musculus castaneus, Mus spretus, Mus spicilegus, and Mus caroli revealed that the ratio of nonsynonymous substitutions to synonymous substitutions on a per-site basis (Ka/Ks) was generally greater than one. The combined observations of no variation at Abpa within M. m: domesticus and uniformly high Ka/Ks values between species suggest that positive directional selection has acted recently at this locus.     

Isolation of an amatoxin binding protein (ABP) different from RNA-polymerase B and C ((author's transl))]

During the isolation of the amatoxin RNA-polymerase B-complex from calf thymus tissue we also isolated a protein (ABP) which shows such strong affinity to [3H)amanin that significant binding occurs at low concentrations (10-7M) of the label. The presence of a new amatoxin-complex is demonstrated by coprecipitation of amatoxin and ABP with ammonium sulphate and the common chromatography on phosphocellulose and Sephadex G-25. The new protein ABP is characterized by denaturating sodium dodecylsulphate-gel electrophoresis. The molecular masses of both main bands - possibly subunits of ABP - are determined as 100000 and 10000 - 15000 Dalton and different from the subunit pattern of RNA-polymerases B and C.     

Biochemical identification of proteasome-associated endonuclease activity in sunflower

Proteasomes have been purified from sunflower hypocotyles. They elute with a molecular mass of 600 kDa from gel filtration columns and two-dimensional gel electrophoresis indicates that the complex contains at least 20 different protein subunits. Peptide microsequencing revealed the presence of four subunits homologous to subunits Beta2, Beta6, Alpha5 and Alpha6 of plant proteasomes. These proteasomes have chymotrypsin-like activity and the highly purified fraction of this complex is associated with an endonuclease activity hydrolyzing Tobacco mosaic virus RNA and Lettuce mosaic virus RNA with a cleavage pattern showing fragments of well-defined size. This is the first evidence of a RNA endonuclease activity associated with plant proteasomes.     

Intrasteric control of AMPK via the gamma1 subunit AMP allosteric regulatory site

AMP-activated protein kinase (AMPK) is a alphabetagamma heterotrimer that is activated in response to both hormones and intracellular metabolic stress signals. AMPK is regulated by phosphorylation on the alpha subunit and by AMP allosteric control previously thought to be mediated by both alpha and gamma subunits. Here we present evidence that adjacent gamma subunit pairs of CBS repeat sequences (after Cystathionine Beta Synthase) form an AMP binding site related to, but distinct from the classical AMP binding site in phosphorylase, that can also bind ATP. The AMP binding site of the gamma(1) CBS1/CBS2 pair, modeled on the structures of the CBS sequences present in the inosine monophosphate dehydrogenase crystal structure, contains three arginine residues 70, 152, and 171 and His151. The yeast gamma homolog, snf4 contains a His151Gly substitution, and when this is introduced into gamma(1), AMP allosteric control is substantially lost and explains why the yeast snf1p/snf4p complex is insensitive to AMP. Arg70 in gamma(1) corresponds to the site of mutation in human gamma(2) and pig gamma(3) genes previously identified to cause an unusual cardiac phenotype and glycogen storage disease, respectively. Mutation of any of AMP binding site Arg residues to Gln substantially abolishes AMP allosteric control in expressed AMPK holoenzyme. The Arg/Gln mutations also suppress the previously described inhibitory properties of ATP and render the enzyme constitutively active. We propose that ATP acts as an intrasteric inhibitor by bridging the alpha and gamma subunits and that AMP functions to derepress AMPK activity.     

The microheterogeneity of androgen-binding protein in rat serum and epididymis is due to differences in glycosylation of their subunits

The microheterogeneity of androgen-binding protein (ABP) from rat serum and epididymis was examined by subjecting purified native or deglycosylated preparations to analysis by one- or two-dimensional polyacrylamide gel electrophoresis (PAGE) followed by electrophoretic transfer to nitrocellulose and immunochemical localization. Analysis of native ABP by one-dimensional sodium dodecyl sulfate-PAGE confirmed earlier observations that it is composed of subunits and that the subunits of serum ABP had higher apparent molecular weights than those of epididymal ABP. Treatment with neuraminidase, N-glycanase, or O-glycanase, alone or in combination, resulted in decreases in the apparent molecular weight of the subunits. These analyses indicated that terminal sialic acid residues and Asn-linked oligosaccharides were present on both subunits of ABP from the two sources. The fact that the greatest reduction in the Mr of the heavy subunit occurred following treatment with all three enzymes provides evidence that O-linked sugars are present on it. While enzyme treatment did not result in the appearance of a single subunit, chemical deglycosylation did (Mr 39,600). The carbohydrate composition of the heavy and light subunits of intact serum and epididymal ABP was 22 and 9% and 19 and 8%, respectively. Analysis by two-dimensional PAGE indicated that both subunits of the ABPs were composed of isoelectric variants. Although ABP from the two sources had several variants in common, differences were also observed. Treatment of the ABPs with the enzymes resulted in a shift of the pI values to a more basic pH range, indicating that carbohydrate removal also removed charged moieties. The most dramatic shift in the pI values of the isoforms occurred when O-glycanase was present in the enzyme mixture, providing further evidence for the presence of O-linked oligosaccharides on ABP. Isoelectric variants were present even after chemical deglycosylation of ABP.     

Chloroplast gene for Mr 32000 polypeptide of photosystem II in Euglena gracilis is interrupted by four introns with conserved boundary sequences

The gene for the Mr 32000 herbicide binding polypeptide of photosystem II has previously been mapped to the 5 kbp EcoRI fragment Eco I of Euglena gracilis chloroplast DNA. The nucleotide sequence of 3324 bp of Eco I, containing the psbA locus, has been determined. This locus encodes a polypeptide of 345 amino acids which is co-linear with, and has 86% derived amino acid sequence homology to sequences derived from four higher plants chloroplast psbA loci. The Euglena psbA gene contains four introns of size 435, 443, 434, and 617 bp. The four introns have conserved boundary sequences of the type previously described in the Euglena chloroplast gene (rbcL) for the large subunit of ribulose-1,5-bisphosphate carboxylase (Koller et al., Cell 36, 545-553, 1984).     

SARS‐CoV‐2 Alpha,Beta, and Delta variants display enhanced Spike‐mediated syncytia formation

Severe COVID‐19 is characterized by lung abnormalities, including the presence of syncytial pneumocytes. Syncytia form when SARS‐CoV‐2 spike protein expressed on the surface of infected cells interacts with the ACE2 receptor on neighboring cells. The syncytia forming potential of spike variant proteins remain poorly characterized. Here, we first assessed Alpha (B.1.1.7) and Beta (B.1.351) spread and fusion in cell cultures, compared with the ancestral D614G strain. Alpha and Beta replicated similarly to D614G strain in Vero, Caco‐2, Calu‐3, and primary airway cells. However, Alpha and Beta formed larger and more numerous syncytia. Variant spike proteins displayed higher ACE2 affinity compared with D614G. Alpha, Beta, and D614G fusion was similarly inhibited by interferon‐induced transmembrane proteins (IFITMs). Individual mutations present in Alpha and Beta spikes modified fusogenicity, binding to ACE2 or recognition by monoclonal antibodies. We further show that Delta spike also triggers faster fusion relative to D614G. Thus, SARS‐CoV‐2 emerging variants display enhanced syncytia formation.     

The apparent molecular weight of androgen-binding protein (ABP) in the blood of immature rats differs from that of ABP in the epididymis

When androgen-binding protein (ABP) in unfractionated immature (20-day old) male rat serum was covalently labeled with the site-specific photoaffinity ligand [3H]17 beta-hydroxy-4,6-androstadien-3-one and analyzed on 5.6% polyacrylamide tube gels containing SDS (SDS-PAGE), a protein of Mr 33,700 +/- 1200 was shown to be specifically labeled. Rat epididymal ABP from unfractionated cytosol analyzed under identical conditions exhibited two androgen-specific peaks of radioactivity, Mr 49,900 +/- 600 and Mr 44,100 +/- 800, which correspond to the previously described subunits of ABP. The apparent molecular weight differences between serum and epididymal ABP were further assessed on preparations of serum ABP that had been partially purified by chromatography on Affi-Gel blue (to remove albumin) and on Sephadex G-150 (to remove other proteins). When these preparations of ABP were photolabeled and analyzed by SDS-PAGE as above, two subunits of Mr 61,700 +/- 1300 and Mr 47,100 +/- 700 were resolved. Serum and epididymal ABP were further purified by androgen affinity chromatography. When these preparations were subjected to SDS-PAGE on slab gels containing 10% polyacrylamide and identified by fluorography of photolabeled ABP or by immunochemical localization following electrophoretic transfer to nitrocellulose, differences in the apparent molecular weight of ABP from the two sources persisted. Immunochemical localization studies on ABPs that had been desialylated with neuraminidase indicated that there was an increased mobility of the subunits, as one would anticipate from removal of carbohydrate. Differences in apparent molecular weight of ABPs from the two sources are likely due to differences in glycosylation.     

Comparison of Site I auxin binding and a 22-kilodalton auxin-binding protein in maize

Several properties of a 43-kilodalton (kDa) auxin-binding protein (ABP) having 22-kDa subunits are shared by a class of auxin binding designated Site I. The spatial distribution of the ABP in the maize (Zea mays L.) mesocotyl corresponds with the distribution of growth induced by naphthalene-1-acetic acid and with the distribution of Site I binding as previously shown by J.D. Walton and P.M. Ray (1981, Plant Physiol. 68, 1334–1338). The greatest abundance of both ABP and Site I activity is at the apical region of the mesocotyl. The ABP and Site I activity co-migrate in isopycnic centrifugation with the endoplasmic-reticulum marker, cytochrome-c reductase. Red light, at low and high fluence, far-red and white light were used to alter the elongation rate of apical 1-cm sections of etiolated maize mesocotyls, the amount of auxin binding, and the abundance of the ABP. Relative changes in auxin binding and the ABP were correlated, but the growth rate was not always correlated with the abundance of the ABP.Abbreviations ABP auxin-binding protein - ER endoplasmic reticulum - FR far-red light - kDa kilodalton - NAA naphthalene-1-acetic acid - PM plasma membrane - R red light - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis     

Salivary androgen-binding protein variation in Mus and other rodents.

We have searched for genetic variation in the expression of salivary androgen-binding protein (ABP) in a wide variety of mice and other rodents. ABP was present in the salivas of mice of all species and subspecies studied. Genetic studies have identified three common variants of the ABP Alpha subunit (Abpaa, Abpab, and Abpac) in Mus musculus populations with distributions that correspond roughly to those of the subspecies studied (domesticus, musculus, and castaneus, respectively). It appears that the ABP a and b polymorphisms conform to the hybrid zone between the domesticus and musculus subspecies characterized by others. Our studies suggest that the presence of Abpab in inbred strains may be due to a M. m. musculus contribution, perhaps via oriental fancy mice bred to European mice in the early lines leading to the common inbred strains. The relatively common occurrence of the ABP a type in other Mus species leads us to conclude that it is the ancestral type in mice. Further, the observation of what amounts to unique alleles in the three different subspecies indicates that microevolution of the protein has occurred. In a broader survey, ABP was also found in the salivas of Murid and Cricetid rodents generally. These findings suggest that ABP has an important functional role in rodent salivas.