Human foamy virus polypeptides: identification of env and bel gene products.

Human foamy virus (HFV) proteins were identified in human cells cultured in vitro by immunoprecipitation and immunoblotting with specific antisera. Among several viral polypeptides, four glycoproteins of approximately 160, 130, 70, and 48 kDa were identified in HFV-infected cells. gp130 was shown to represent the intracellular env precursor, and gp70 and gp48 were shown to represent the external and transmembrane env proteins, respectively. The nature of gp160, which shares sequences with the env, bel1, and bel2 proteins, is not yet resolved. In addition, a p62 identified with bel1- and bel2-specific antisera likely corresponds to the bet gene product.     

Characterization of Magnaporthe oryzae chrysovirus 1 structural proteins and their expression in Saccharomyces cerevisiae

Magnaporthe oryzae chrysovirus 1 (MoCV1), which is associated with an impaired growth phenotype of its host fungus, harbors four major proteins: P130 (130 kDa), P70 (70 kDa), P65 (65 kDa), and P58 (58 kDa). N-terminal sequence analysis of each protein revealed that P130 was encoded by double-stranded RNA1 (dsRNA1) (open reading frame 1 [ORF1] 1,127 amino acids [aa]), P70 by dsRNA4 (ORF4; 812 aa), and P58 by dsRNA3 (ORF3; 799 aa), although the molecular masses of P58 and P70 were significantly smaller than those deduced for ORF3 and ORF4, respectively. P65 was a degraded form of P70. Full-size proteins of ORF3 (84 kDa) and ORF4 (85 kDa) were produced in Escherichia coli. Antisera against these recombinant proteins detected full-size proteins encoded by ORF3 and ORF4 in mycelia cultured for 9, 15, and 28 days, and the antisera also detected smaller degraded proteins, namely, P58, P70, and P65, in mycelia cultured for 28 days. These full-size proteins and P58 and P70 were also components of viral particles, indicating that MoCV1 particles might have at least two forms during vegetative growth of the host fungus. Expression of the ORF4 protein in Saccharomyces cerevisiae resulted in cytological changes, with a large central vacuole associated with these growth defects. MoCV1 has five dsRNA segments, as do two Fusarium graminearum viruses (FgV-ch9 and FgV2), and forms a separate clade with FgV-ch9, FgV2, Aspergillus mycovirus 1816 (AsV1816), and Agaricus bisporus virus 1 (AbV1) in the Chrysoviridae family on the basis of their RdRp protein sequences.     

Posttranslational processing of polysaccharide lyase: maturation route for gellan lyase in Bacillus sp. GL1

Cells of Bacillus sp. GL1 extracellularly secrete a gellan lyase with a molecular mass of 130 kDa responsible for the depolymerization of a heteropolysaccharide (gellan), although the gene is capable of encoding a huge protein with a molecular mass of 263 kDa. A maturation route for gellan lyase in the bacterium was determined using anti-gellan lyase antibodies. The fluid of the bacterial exponentially growing cultures on gellan contained two proteins with molecular masses of 260 and 130 kDa, both of which reacted with the antibodies. The 260 kDa protein was purified from the cultured fluid and characterized. The protein exhibited gellan lyase activity and showed similar enzyme properties, such as optimal pH and temperature, thermal stability, and substrate specificity, to those of the 130 kDa gellan lyase. The N-terminal amino acid sequences of the 260 and 130 kDa enzymes were found to be identical. Determination of the C-terminal amino acid of the 130 kDa enzyme indicated that the 260 kDa enzyme is cleaved between the 1205Gly and 1206Leu residues to yield the mature form (130 kDa) of the gellan lyase. Therefore, the mature enzyme consists of 1170 amino acids (36Ala-1205Gly) with a molecular weight of 125,345, which is in good agreement with that calculated from SDS-PAGE analysis. Judging from these results, gellan lyase is first synthesized as a preproform (263 kDa) and then secreted as a precursor (260 kDa) into the medium through cleavage of the signal peptide. Finally, the precursor is post-translationally processed into the N-terminal half domain of 130 kDa as the mature form, the function of C-terminal half domain being unclear.     

Cellular localization and characterization of proteins that bind high density lipoprotein.

High density lipoprotein (HDL) stimulates excretion of excess intracellular cholesterol from cells, presumably by interacting with a cell-surface receptor. A 110 kDa membrane protein that is a candidate for the HDL receptor has been identified by ligand blot analysis. In this study we determined the cellular localization of this and other HDL-binding proteins and characterized their properties. The plasma membranes (PM) of cultured bovine aortic endothelial cells were labeled with trace amounts of [3H]cholesterol, and cell homogenates were fractionated on sucrose and Percoll gradients. Ligand blot analysis of homogenates of cultured bovine aortic endothelial cells demonstrated that cells contain multiple proteins that bind HDL3, including a major membrane protein with an apparent M(r) of 110 kDa and two minor ones with M(r) of 105 and 130 kDa. The gradient distribution of the 105, 110, and 130 kDa HDL-binding proteins mirrored that of labeled cholesterol and 5'-nucleotidase, both PM markers. Treatment of intact cells with the water-soluble cross-linker bis(sulfosuccinimidyl)suberate abolished the HDL binding activity of the 110 and 130 kDa proteins but not that of the 105 kDa protein. These findings suggest that the 105, 110, and 130 kDa HDL-binding proteins are localized to the PM and that at least two of these proteins are exposed to the extracellular fluid. Solubilized 110 and 130 kDa proteins were retained on wheat-germ agglutinin and abrin lectin columns, showing that they are glycoproteins. The cellular localization and physical properties of the 110 and 130 kDa proteins suggest that they may play a role in binding of HDL to the cell surface.     

Comparative toxicity of Bacillus thuringiensis var. israelensis crystal proteins in vivo and in vitro

Bacillus thuringiensis var. israelensis crystal proteins were purified by FPLC on a Mono Q column to yield 130, 65, 28, 53, 30-35 and 25 kDa proteins. All the purified proteins killed Aedes aegypti larvae after citrate precipitation, but the 65 kDa protein was the most toxic. A precipitated mixture of 27 and 130 kDa proteins was almost as toxic as solubilized crystals. In assays against a range of insect cell lines, the activated form (25 kDa) of the 27 kDa protein was generally cytotoxic with the lowest LC50 values in vitro. By contrast, the activated forms of the 130 kDa and 65 kDa protoxins (53 kDa and 30-35 kDa proteins, respectively) were much more specific than the 25 kDa protein in their action on dipteran cells, and each showed a unique toxicity profile which, in the case of the 130 kDa preparation, was restricted to Anopheles and Culex cell lines.     

Novel non-toxic isolates of Bacillus thuringiensis

Argentinean isolates INTA Mo14–4 and INTA 33–5 of Bacillus thuringiensis were characterized. INTA 33–5 (serovar kenyae ) had an amorphous crystal containing proteins of 200 and 130 kDa. INTA Mo14–4 (serovar darmstadiensis ) had a bipyramidal crystal and a bar-shaped inclusion, containing proteins of 130, 60 and 40 kDa. Crystals of both strains showed no toxicity to lepidopteran, dipteran and coleopteran targets. Trypsin digestion of solubilized crystal proteins of INTA 33–5 produced four peptides (≈65 kDa). No putative δ–endotoxin was detected in Mo14–4. Both isolates showed unique plasmid patterns. Southern analyses showed no homology to four known cursive genes. These results indicate the uniqueness of two novel strains of B. thuringiensis which, in turn, confirm the great diversity of this species.     

Characterization of Iarvicidal toxin protein from Bacillus thuringiensis serovar japonensis strain Buibui specific for scarabaeid beetles

The δ-endo toxin proteins from Bacillus thuringiensis which kill the larvae of various scarabaeid beetles such as Anomala cuprea, A. rufocuprea and Popillia japonica were purified by DEAE ion exchange chromatography. A protein with a molecular size of 130 kDa was purified. During the purification a minor peak was also detected which was estimated to be 67 kDa by SDS-PAGE. Both 130 and 67 kDa proteins showed larvicidal activity against A. cuprea. The lethal concentration of the 130 kDa protein which killed 50% of the larvae tested (LC₅₀) against A. cuprea was 2 μg g¹ compost. A comparison by SDS-PAGE of the V8 protease digestion pattern of the 130 and 67 kDa larvicidal proteins showed that proteolytic resistant core peptides of approximately 60 kDa molecular size were resulted. The N -terminus amino acid sequence of the 130 and 67 kDa proteins was determined to be NH₂-XXPNNQNEYEIIDAL and NH₂-XSRNPGTFI, respectively, which is not identical to the sequence of CryIA, CryIB, CryIC and CryIII proteins.     

LRP130, a protein containing nine pentatricopeptide repeat motifs, interacts with a single-stranded cytosine-rich sequence of mouse hypervariable minisatellite Pc-1.

Recently, we have identified and purified minisatellite DNA binding proteins (MNBPs) that bind to the mouse hypervariable minisatellite Pc-1, from NIH3T3 cells. This study describes the isolation and characterization of a mouse leucine-rich protein (mLRP130) as one of the MNBPs that binds to the C-rich strand of Pc-1. The mLRP130 cDNA was demonstrated to encode a polypeptide of 1306 amino-acid residues with a deduced molecular mass of 137 kDa, and the mLRP130 mRNA is detected in various organs, including heart, brain, liver, skeletal muscle, kidneys and testes. The mLRP130 protein has nine copies of pentatricopeptide repeat (PPR) motifs that are considered to serve as protein-protein interactions. Two forms of the mLRP130 protein were detected in NIH3T3 cells with an approximate molecular mass of 140 kDa (mLRP130) and 100 kDa (mLRP130der), and were detected mainly in nuclear and cytoplasmic fractions, respectively. Immunofluorescence microscopic analysis demonstrated dominant localization of mLRP130 at the perinuclear region, and also in the nucleus and cytoplasm with dot- or squiggle-like staining. The immunoprecipitated mLRP130 bound to the single-stranded d(CTGCC)8, but not to its complementary G-rich strand of d(GGCAG)8 or double-stranded form. Possible biological roles of mLRP130 are discussed in association with the stability of minisatellite DNA sequences.     

Isolation of the epidermal growth factor from the shrew submaxillary gland

Entomocidal crystals produced by Bacillus thuringiensis ssp. israelensis are formed by two proteins with molecular masses of 130 and 28 kDa, whereas the protein with a molecular mass of 70 kDa appears as a result of 130 kDa protein limited proteolysis by admixtures of bacterial proteinases in the course of its dissolution. The comparison of the N-terminal sequences of the protein with molecular mass of 70 kDa (Met-Glu-Asn-Xaa-Pro-Leu-Asp-Thr-Leu-Ser-Ile-Val-Asn-Glu-Thr-Asp) and that of 28 kDa (Met-Glu-Asn-Leu-Asn-[Phe]-[Trp]-Pro-Leu-Gln-Asp-Ile-Lys-Val-Asn-Pro) reveals only marginal similarity between them (only 4 identical residues among 16 aligned). Both B. thuringiensis israelensis crystal-forming proteins appear hardly related to those contained in the crystal produced by other B. thuringiensis subspecies, e.g. kurstaki. It might be concluded that at least some of the entomocidal proteins found in the crystalline inclusion bodies of various B. thuringiensis subspecies revealed rather strong variations in their primary structures that facilitate their adaptation to different hosts.

Bacillus thuringiensis ssp. israelensis δ-Endotoxin Entomocidal crystal Insecticide Mosquito     

Characterization of mosquito larvicidal parasporal inclusions of a Bacillus thuringiensis serovar higo strain

The parasporal inclusion proteins of the type strain of Bacillus thuringiensis serovar higo (H44), that have moderate mosquitocidal activity, were characterized. The purified parasporal inclusions, spherical in shape, were examined for activity against the two mosquito species, Culex pipiens molestus and Anopheles stephensi and the moth-fly, Telmatoscopus albipunctatus . The LC₅₀ values of the inclusion for the two mosquitoes were 3·41 and 0·15 μg ml⁻¹, respectively. No mortality was shown for T. albipunctatus larvae by the inclusions at concentrations up to 1 mg ml⁻¹. Solubilized parasporal inclusions exhibited no haemolytic activity against sheep erythrocytes. Parasporal inclusions consisted of eight proteins with molecular masses of 98, 91, 71, 63, 59, 50, 44 and 27 kDa. Of these, the 50 and 44 kDa proteins were the major components. Analysis with immunoblotting revealed that, among several inclusion proteins of B. thuringiensis serovar israelensis, only two proteins of 130 kDa and 110 kDa reacted weakly with antibodies against higo proteins. N-terminal amino acid sequences of the 98, 91, and 71 kDa proteins showed 85–100% identity to those of the two established Cry protein classes, Cry4A and Cry10A.     

Domain organization of p130, PLC-related catalytically inactive protein, and structural basis for the lack of enzyme activity.

The 130-kDa protein (p130) was isolated as a novel inositol 1,4, 5-trisphosphate [Ins(1,4,5)P3]-binding protein similar to phospholipase C-delta1 (PLC-delta1), but lacking catalytic activity [Kanematsu, T., Takeya, H., Watanabe, Y., Ozaki, S., Yoshida, M., Koga, T., Iwanaga, S. & Hirata, M. (1992) J. Biol. Chem. 267, 6518-6525; Kanematsu, T., Misumi, Y., Watanabe, Y., Ozaki, S., Koga, T., Iwanaga, S., Ikehara, Y. & Hirata, M. (1996) Biochem. J. 313, 319-325]. To test experimentally the domain organization of p130 and structural basis for lack of PLC activity, we subjected p130 to limited proteolysis and also constructed a number of chimeras with PLC-delta1. Trypsin treatment of p130 produced four major polypeptides with molecular masses of 86 kDa, 55 kDa, 33 kDa and 25 kDa. Two polypeptides of 86 kDa and 55 kDa started at Lys93 and were calculated to end at Arg851 and Arg568, respectively. Using the same approach, it has been found that the polypeptides of 33 kDa and 25 kDa are likely to correspond to regions between Val569 and Arg851 and Lys869 and Leu1096, respectively. All the proteolytic sites were in interconnecting regions between the predicted domains, therefore supporting domain organization based on sequence similarity to PLC-delta1 and demonstrating that all domains of p130, including the unique region at the C-terminus, are stable, tightly folded structures. p130 truncated at either or both the N-terminus (94 amino acids) and C-terminus (851-1096 amino acids) expressed in COS-1 cells showed no catalytic activity, indicating that p130 has intrinsically no PLC activity. A number of chimeric molecules between p130 and PLC-delta1 were constructed and assayed for PLC activity. It was shown that structural differences in interdomain interactions exist between the two proteins, as only some domains of p130 could replace the corresponding structures in PLC-delta1 to form a functional enzyme. These results suggest that p130 and the related proteins could represent a new protein family that may play some distinct role in cells due to the capability of binding Ins(1,4,5)P3 but the lack of catalytic activity.     

Mass spectrometric sequencing of endotoxin proteins of Bacillus thuringiensis ssp. konkukian extracted from polyacrylamide gels

The amino acid sequences of the crystal proteins of Bacillus thuringiensis ssp. konkukian strain HL-47 are unknown. We used 1-D denaturing polyacrylamide electrophoresis, nano-ESI-Q-TOF-MS, and protein database searching to analyze these proteins. On SDS-PAGE gels, a preparation of purified crystal proteins exhibited 110, 102, 76, 55, 37, and 30 kDa protein bands. Immunoblotting of the gel with antiserum raised to this preparation revealed that four crystal proteins, of 110, 102, 55, and 37 kDa, reacted with the specific antiserum. The 102-kDa major protein reacted strongly. The other crystal proteins showed weak immunoreactivity. The 102 and 55 kDa proteins were analyzed by ESI-MS. The internal amino acid sequence of the 102-kDa major protein has similarity to the sequences of the surface layer protein of B. thuringiensis ssp. finitimus and B. anthracis. However, the internal amino acid sequences of the 55 kDa protein did not show any homology to proteins in the databases. Proteomic analysis of these proteins leads to the conclusion that the sequence data provided the protein databases of the crystal proteins of the konkukian ssp.     

Methyl-esterified proteins in a mammalian cell line

Methyl esterification of carboxylic acid residues in intact mouse S49 lymphoma cells was examined, and at least 24 proteins were found to be modified. Cell fractionation revealed that a distinct set of these proteins could be found in each of the four fractions. Nuclei contained 11 methyl-esterified proteins at 12, 15.5, 18, 19, 39, 41, 45, 70, 90, 105, and 130 kilodaltons (kDa). Five proteins copurified with the plasma membrane/mitochondrial fraction at 13, 24, 25, 27, and 28 kDa. Two proteins at 32 and 56 kDa were in the microsomal fraction, and six were soluble at 16.5, 21, 24, 26, 34, and 36 kDa. Eleven of these proteins were [3H]methyl esterified when cell homogenates were incubated with S-adenosyl-L-[methyl-3H]methionine. The steady-state level of methyl group incorporation into protein in intact cells was approximately 118 pmol/mg of protein. Assuming the average protein is 40 kDa, there appears to be 1 methyl group per 210 proteins. This was compared to phosphorylation which gave approximately one phosphoryl group for every four proteins. Exogenously added L-[methyl-3H]methionine equilibrated with the cellular S-adenosylmethionine pool within 30 min which was sufficiently rapid to allow the rate of methyl group turnover to be determined. Most methyl-esterified proteins demethylated in a pulse--chase experiment with half-lives ranging from 2.6 to 9.3 h. When protein syn thesis was blocked with puromycin, amino acid backbone incorporation of methionine was reduced to 2% of control. Methyl group incorporation, however, was 39% of the control.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nucleotide sequence of the gene coding for a 130-kDa mosquitocidal protein of Bacillus thuringiensis israelensis

The nucleotide sequence of pVB131 containing the gene coding for a 130-kDa Bacillus thuringiensis israelensis (B.t.isr) mosquitocidal protein was determined. The pVB131 plasmid was constructed by Sekar and Carlton [Gene 33 (1985) 151-158]. Our sequencing revealed only one open reading frame large enough to code for a protein of 130 kDa. The translation start site was determined by sequencing the protein isolated from B.t.isr. The amino acid sequence of the protein was deduced from the nucleotide sequence, and its Mr was determined as 128,505. Immunological and biochemical analyses of B.t.isr mosquitocidal proteins indicated that the 130-kDa protein coded by pVB131 was indeed expressed in B.t.isr. Comparing the peptide sequence of the 130-kDa B.t.isr toxin with the sequences of other B.t. toxins having activities specific to lepidopteran species showed that several domains were highly homologous. This suggests that they are evolutionarily related to each other, and in the evolutionary process the sequences in the homologous domains that are important to the insecticidal activity have been conserved.     

Partial characterization of vitellin and localization of vitellogenin production in the terrestrial isopod, Armadillidium vulgare

Vitellins were purified separately from ovaries and eggs of the isopod, Armadillidium vulgare. Ovarian vitellin consisted of at least six proteins with relative molecular masses of 205, 200, 185, 180, 122 and 112 kDa. The larger four proteins disappeared in eggs within a week after oviposition and a 59-kDa protein appeared thereafter. The amino-terminal amino acid sequences of these vitellin proteins were identical except for the ovarian 112 kDa, egg 112 kDa and 59 kDa proteins, and showed considerable similarity to those of known vitellogenins from other animals. Comparison of tryptic peptide maps of the 122 and 112 kDa proteins from eggs on reversed-phase HPLC and sequence identification of two randomly selected peaks having the same retention times indicated that two peptides were mostly similar in sequence. PCR-assisted cloning of the 5' region of a cDNA (591 bp) encoding vitellogenin revealed the presence of a signal peptide consisting of 16 amino acid residues and clarified the structural relationship among the protein components except for the ovarian 112 kDa and the egg 59 kDa proteins. Northern blot analysis revealed that the fat body is the main vitellogenin producing organ.     

Identification and analysis of the genes coding for the putative pyruvate dehydrogenase enzyme complex in Acholeplasma laidlawii.

A monospecific antibody recognizing two membrane proteins in Acholeplasma laidlawii identified a plasmid clone from a genomic library. The nucleotide sequence of the 4.6-kbp insert contained four sequential genes coding for proteins of 39 kDa (E1 alpha, N terminus not cloned), 36 kDa (E1 beta), 57 kDa (E2), and 36 kDa (E3; C terminus not cloned). The N termini of the cloned E2, E1 beta, and native A. laidlawii E2 proteins were verified by amino acid sequencing. Computer-aided searches showed that the translated DNA sequences were homologous to the four subenzymes of the pyruvate dehydrogenase complexes from gram-positive bacteria and humans. The plasmid-encoded 57-kDa (E2) protein was recognized by antibodies against the E2 subenzymes of the pyruvate and oxoglutarate dehydrogenase complexes from Bacillus subtilis. A substantial fraction of the E2 protein as well as part of the pyruvate dehydrogenase enzymatic activity was associated with the cytoplasmic membrane in A. laidlawii. In vivo complementation with three different Escherichia coli pyruvate dehydrogenase-defective mutants showed that the four plasmid-encoded proteins were able to restore pyruvate dehydrogenase enzyme activity in E. coli. Since A. laidlawii lacks oxoglutarate dehydrogenase and most likely branched-chain dehydrogenase enzyme complex activities, these results strongly suggest that the sequenced genes code for the pyruvate dehydrogenase complex.     

Flagellar proteins and type III-exported virulence factors are the predominant proteins secreted into the culture media of Salmonella typhimurium

We analysed all major proteins secreted into culture media from Salmonella typhimurium. Proteins in culture supernatants were collected by trichloroacetic acid precipitation, separated in SDS-polyacrylamide gels and analysed by amino acid sequencing. Wild-type strain SJW1103 cells typically gave rise to nine bands in SDS gels: 89, 67, 58, 52, 50, 42, 40, 35 and (sometimes) 28 kDa. A search of the sequences in the available databases revealed that they were either flagellar proteins or virulence factors. Six of them were flagella specific: FlgK or HAP1 (58 kDa), FliC or flagellin (52 kDa), FliD or HAP2 (50 kDa), FlgE or hook protein (42 kDa), FlgL or HAP3 (35 kDa) and FlgD or hook-cap protein (28 kDa). The other four bands were specific for virulence factors: SipA (89 kDa), SipB (67 kDa), SipC (42 kDa) and InvJ (40 kDa). The 42 kDa band was a mixture of FlgE and SipC. We also analysed secreted proteins from more than 30 flagellar mutants, and they were categorized into four groups according to their band patterns: wild type, mot type, polyhook type and master gene type. Virulence factors were constantly secreted at a higher level in all flagellar mutants except a deltamot (motAB deletion) mutant, in which the amounts were greatly reduced. A new morphological pathway of flagellar biogenesis including protein secretion is presented.     

Specific interactions of HeLa cell proteins with proposed translation domains of the poliovirus 5'' noncoding region.

To determine which sequences or structures in the poliovirus 5' noncoding region (5'NCR) are involved in binding proteins used for internal ribosome binding and protein synthesis initiation, translation competition assays were performed in rabbit reticulocyte lysates in the presence and absence of HeLa cell extract. The results revealed two functional domains in the poliovirus 5'NCR. One, requiring nucleotides (nts) 457 to 626, binds proteins that are required for translation of all mRNAs and that are present in both reticulocyte lysates and HeLa cell extracts. Another, contained within nts 286 to 456, interacts with proteins that are specific for poliovirus translation and are present in HeLa cells but not in significant amounts in rabbit reticulocyte lysates. In order to detect HeLa cell proteins that interact stably with the 5'NCR of poliovirus, UV cross-linking was used. At least four major protein-RNA complexes were identified, three of which were shown by RNA competition analysis to bind specifically to defined domains within the 5'NCR. Protein A (54 kDa) cross-linked to RNA sequences and/or structures located between nts 457 and 626; proteins B (48 kDa) and C (38 kDa) bound to nts 286 to 456.     

Structural features of crystal-forming proteins produced by Bacillus thuringiensis subspecies israelensis

Entomocidal crystals produced by Bacillus thuringiensis ssp. israelensis are formed by two proteins with molecular masses of 130 and 28 kDa, whereas the protein with a molecular mass of 70 kDa appears as a result of 130 kDa protein limited proteolysis by admixtures of bacterial proteinases in the course of its dissolution. The comparison of the N-terminal sequences of the protein with molecular mass of 70 kDa (Met-Glu-Asn-Xaa-Pro-Leu-Asp-Thr-Leu-Ser-Ile-Val-Asn-Glu-Thr-Asp) and that of 28 kDa (Met-Glu-Asn-Leu-Asn-[Phe]-[Trp]-Pro-Leu-Gln-Asp-Ile-Lys-Val-Asn-Pro) reveals only marginal similarity between them (only 4 identical residues among 16 aligned). Both B. thuringiensis israelensis crystal-forming proteins appear hardly related to those contained in the crystal produced by other B. thuringiensis subspecies, e.g. kurstaki. It might be concluded that at least some of the entomocidal proteins found in the crystalline inclusion bodies of various B. thuringiensis subspecies revealed rather strong variations in their primary structures that facilitate their adaptation to different hosts.Bacillus thuringiensis ssp. israelensis δ-EndotoxinEntomocidal crystalInsecticideMosquito     

Three immunologically similar atrial natriuretic factor receptors

One of the atrial natriuretic factor (ANF) receptors is a 180 kDa protein (180 kDa mGC) which possesses the extraordinary characteristic of being bifunctional: it is both a receptor and a guanylate cyclase. In addition to the 180 kDa mGC, there exists another 120–130 kDa protein which is also bifunctional and a 120 kDa disulfide-linked dimeric cell surface protein that is an ANF receptor, but is not a part of guanylate cyclase. A fundamental question that needs to be resolved is: Are these three apparently biochemically distinct ANF receptors structurally similar? With the aid of affinity crosslinking techniques, a highly specific antibody to the 180 kDa mGC, and GTP-affinity techniques, we now demonstrate the presence of three immunologically similar proteins in rat adrenal gland and testes. These proteins migrate as 180 kDa, 130 kDa and 65 kDa under denaturing sodium dodecyl sulfate polyacrylamide gel electrophoresis and specifically bind ANF, raising one or more of the following possibilities about their relationships: 1) Degradation of 180 kDa to 130 kDa and 65 kDa occurs during purification; 2) 180 kDa bears a precursor-product relationship with 130 kDa and 65 kDa, suggesting the role of a protease in the processing procedure; 3) these proteins are a result of gene splicing; or 4) they are the products of three separate, but very closely related genes.