Purification of the receptor for the N-acetyl-d-glucosamine specific adhesin of Mannheimia haemolytica from bovine neutrophils

The GlcNAc-specific adhesin from Mannheimia haemolytica (MhA) has been shown to participate in pathogenicity of mannheimiosis due to its capacity to adhere to tracheal epithelial cells and activate the oxidative burst of bovine neutrophils. In this work, we purified the MhA receptor from bovine neutrophils (MhAr) by affinity chromatography on MhA-Sepharose. The MhAr, which corresponded to approximately 2% of the protein from cell lysate, is a glycoprotein mainly composed of Glu, Ala, Ser, Gly, and Asp, without cysteine. The glycan portion, which corresponds to 20% by weight, is composed of GalNAc, GlcNAc, Man, Gal, and NeuAc. The receptor is a 165-kDa glycoprotein, as determined by molecular sieve chromatography under native conditions; SDS-PAGE analysis shows a heterodimer of 83 and 80 kDa subunits. This work suggests that the GlcNAc-containing receptor plays a relevant role by activating bovine neutrophils through non-opsonic mechanisms.     

Purification of a new type high molecular weight receptor (type V receptor) of transforming growth factor beta (TGF-beta) from bovine liver. Identification of the type V TGF-beta receptor in cultured cells.

A 400-kDa transforming growth factor beta (TGF-beta) receptor was purified from plasma membranes of bovine liver using Triton X-100 extraction, wheat germ lectin-Sepharose 4B affinity chromatography, DEAE-cellulose anion exchange chromatography, and Sepharose CL-4B gel filtration chromatography. This procedure yielded approximately 20 micrograms of the receptor from 1 kg of bovine liver. During purification, the 400-kDa TGF-beta receptor was detected by a cross-linking assay in which the TGF-beta receptor-125I-TGF-beta complex was cross-linked by disuccinimidyl suberate, a bifunctional reagent, and analyzed by 5.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography. This novel 400-kDa TGF-beta receptor was also identified on cultured cells including cells reported to lack the type III receptor. The 400-kDa TGF-beta receptor, a nonproteoglycan glycoprotein, appears to be distinct from TGF-beta receptors (types I, II, III, and IV) previously identified on cultured cells and is designated as the type V receptor. The 400-kDa TGF-beta receptor as well as type I, II, and III receptors underwent internalization upon 125I-TGF-beta binding in mink lung epithelial cells.     

Isolation and characterization of the potential receptor for wheat germ agglutinin from human neutrophils

Neutrophils participate in host protection and central to this process is the regulation of oxidative mechanisms. We purified by affinity chromatography the receptor for the GlcNAc-specific WGA from CD14+ CD16+ cell lysates (WGAr). The receptor is a 141 kDa glycoprotein constituted by two subunits of 78 and 63 kDa. It is mainly composed of Ser, Asx, and Gly, and, in a minor proportion, His, Cys, and Pro. Its glycan portion contains GlcNAc, Gal, and Man; NeuAc and GalNAc were identified in a minor proportion. The amino acid sequence of the WGA receptor was predicted from tryptic peptides by MALDI-TOF, both subunits showed homology with cytokeratin type II (26 and 29% for the 78 and 63 kDa subunits, respectively); the 78 kDa subunit showed also homology with the human transferrin receptor (24%). Antibodies against WGAr induce higher oxidative burst than WGA, determined by NBT reduction; however, this effect was inhibited (p < 0.05) with GlcNAc suggesting that WGAr participates as mediator in signal transduction in neutrophils.     

Carbohydrates in mammalian tryptophanyl-tRNA synthetase.

Homogeneous preparations of bovine tryptophanyl-tRNA synthetase (EC 6.1.1.2) contain monosaccharides (mannose, fucose, galactose, N-acetylglucosamine) as revealed by liquid chromatography. Their content comprises 2.5-3.0% (w/w) of the enzyme composed of two subunits (60 kDa x 2). The same set of sugars was detected in elastase and CNBr-generated fragments (with molecular masses of approx. 40 kDa and 30 kDa, respectively). It is concluded that bovine tryptophanyl-tRNA synthetase, in addition to being a metallo- and phosphoprotein, is also a glycoprotein.     

Purification and properties of the major sialoglycoprotein of the milk fat globule membrane

The major periodate-Schiff positive component (glycoprotein-2) of bovine milk fat globule membranes (MFGM) has been purified by extraction of washed cream with chloroform/methanol followed by chromatography on Sephadex G-200 in sodium dodecyl sulfate. The glycoprotein is > 95% pure by polyacrylamide electrophoresis in dodecyl sulfate and shows the same prominent component at gel percentages of from 5 to 12.5. The molecular weight obtained by extrapolation of the apparent molecular weights on these gels to higher gel percentages was 70,000. An apparent molecular weight of 105,000 was obtained by gel filtration in 1% dodecyl sulfate on Sepharose 4B. The glycoprotein contains 50% carbohydrate by weight, with sialic acid (30.5%), N-acetylglucosamine (22.3%), galactose (15.9%), N-acetylgalactosamine (14.0%), mannose (11.1%), and fucose (5.8%) being the major monosaccharides. Leucine, glutamic acid, and glycine are the major amino acids. Affinity chromatography of deoxycholate-solubilized MFGM indicates that glycoprotein-2 is not the major concanavalin A receptor of these membranes.     

Cloning,Identification and Functional Characterization of Bovine Free Fatty Acid Receptor-1 (FFAR1/GPR40) in Neutrophils

Long chain fatty acids (LCFAs), which are ligands for the G-protein coupled receptor FFAR1 (GPR40), are increased in cow plasma after parturition, a period in which they are highly susceptible to infectious diseases. This study identified and analyzed the functional role of the FFAR1 receptor in bovine neutrophils, the first line of host defense against infectious agents. We cloned the putative FFAR1 receptor from bovine neutrophils and analyzed the sequence to construct a homology model. Our results revealed that the sequence of bovine FFAR1 shares 84% identity with human FFAR1 and 31% with human FFAR3/GPR41. Therefore, we constructed a homology model of bovine FFAR1 using human as the template. Expression of the bovine FFAR1 receptor in Chinese hamster ovary (CHO)-K1 cells increased the levels of intracellular calcium induced by the LCFAs, oleic acid (OA) and linoleic acid (LA); no increase in calcium mobilization was observed in the presence of the short chain fatty acid propionic acid. Additionally, the synthetic agonist GW9508 increased intracellular calcium in CHO-K1/bFFAR1 cells. OA and LA increased intracellular calcium in bovine neutrophils. Furthermore, GW1100 (antagonist of FFAR1) and U73122 (phospholipase C (PLC) inhibitor) reduced FFAR1 ligand-induced intracellular calcium in CHO-K1/bFFAR1 cells and neutrophils. Additionally, inhibition of FFAR1, PLC and PKC reduced the FFAR1 ligand-induced release of matrix metalloproteinase (MMP)-9 granules and reactive oxygen species (ROS) production. Thus, we identified the bovine FFAR1 receptor and demonstrate a functional role for this receptor in neutrophils activated with oleic or linoleic acid.     

The isolation and properties of a second glycoprotein (LGP-II) from the articular lubricating fraction from bovine synovial fluid.

A high-molecular-weight glycoprotein (LGP-I) was shown [Swann, Sotman, Dixon & Brooks (1977) Biochem. J. 161, 473--485] to be the major constituent in the articular lubricating fraction from bovine synovial fluid. In addition to the LGP-I component, a second glycoprotein (LGP-II) was also present. After fractionation of bovine synovial fluid by sequential sedimentation in CsCl density gradients, the LGP-I and LGP-II components were separated by gel-permeation chromatography. The LGP-II component was then purified by chromatography on DEAE Bio-Gel A and Bio-Gel P-150. The molecular weight of the LGP-II component was 48,800 calculated from sedimentation-equilibrium measurements. Amino acids represented 53% (w/w) and carbohydrate constituents 36% (w/w) of the molecule. Glutamic acid and lysine (144 and 100 residues/1000 residues) were the major amino acids. Glucosamine, mannose, galactose and N-acetylneuraminic acid [representing 8.0, 6.6, 9.5 and 11.9% (w/w) respectively] were the only carbohydrate constituents detected. Immunodiffusion analysis showed that LGP-II component did not form a detectable precipitin line with antiserum to bovine serum. It appears likely, therefore, that this glycoprotein is synthesized by the joint tissues and is not derived from serum.     

Bovine follitropin. Isolation and characterization of the native hormone and its alpha and beta subunits

1) A reproducible procedure was developed for the purification of bovine follitropin. 2) The method involved ammonium sulfate precipitation, ion exchange and adsorption chromatography, concanacaline-A-Sepharose chromatography and gel filtration. 3) A specific radioligand receptor assay was used to monitor each chromatographical step. 4) The potency of highly purified bovine follitropin as measured by Steelman and Pohley bioassay was 62 times the NIH-FSH-B1 standard preparation. 5) Contaminations of bovine follitropin by other glycoprotein hormones such as thyrotropin and lutropin amounted to 3 and 0.45 per cent by weight respectively as measured by specific radioimmunoassays and radioligand receptor assays. 6) The subunits alpha and beta of bovine follitropin were obtained by incubation in acidic urea, the chains being then separated by anion exchange chromatography. The subunits were subjitted to complete characterization. The amino-terminal residue of the alpha subunit is phenylalanine while a half cystine residue was found at the aminoterminal end of the beta chain. 8) Cross-contamination of the alpha and beta subunit preparations was measured by specific radioimmunoassays and amounted to 0.02 and 0.1 per cent by weight respectively.     

Spin-Trapping and Chemiluminescence Studies of Neutrophils from a Holstein-Friesian Calf with Bovine Leukocyte Adhesion Deficiency

The ability of neutrophils from a Holstein-Friesian calf with bovine leukocyte adhesion deficiency (the proband with a genetic deficiency of the Mac-1 (CD11b/CD18) glycoprotein corresponding to the receptor of complement iC3b) to generate oxygen radicals was examined using electron spin resonance spectrometry (ESR) combined with a spin-trapping technique and luminol-dependent chemiluminescence spectrometry. When the neutrophils were stimulated with phorbol 12-myristate 13-acetate (PMA), an ESR spectrum confirming the generation of superoxide anions (O₂^-) was clearly observed in both healthy and diseased calves. However, when the neutrophils were stimulated by opsonized zymosan, appearance of the ESR spectrum was recognized in the healthy calves but not in the diseased calf. Similar results were obtained from chemiluminescence experiments.     

Isolation and characterization of the receptor on human neutrophils that mediates cellular adherence

The receptor on human neutrophils (polymorphonuclear leukocytes or PMN) that mediates cellular adherence has been purified from the peripheral blood PMN obtained from an individual with chronic myelogenous leukemia (CML). This receptor consists of two noncovalently associated subunits, designated alpha M (Mac-1 alpha, CD11b) (Mr = 170,000) and beta (Mac-1 beta, CDw18) (Mr = 100,000), respectively, which are identical on normal and CML PMN. The subunits were purified by monoclonal antibody 60.1-Sepharose (anti-alpha M) affinity chromatography and separated in 5-nmol quantities by high pressure liquid chromatography on a TSK-4000 gel filtration column. Subunits were characterized by amino acid composition, NH2-terminal amino acid sequence, and carbohydrate content. The NH2-terminal sequence of the human PMN alpha M subunit contains regions of homology with the human platelet glycoprotein IIb alpha. We conclude that nanomole amounts of individual alpha M and beta subunits of the receptor on human PMN that mediates cellular adherence can be isolated and separated using CML PMN.     

Purification and receptor binding properties of complexes between lutropin and monovalent antibodies against its alpha subunit.

A complex between bovine lutropin (LH) and monovalent antibodies (Fab fragments) directed against its alpha subunit, which is common to the glycoprotein hormones, has been purified by gel filtration and chromatography on concanavalin A-Sepharose. The complex is heterogenous with respect to molecular size; 70--80% of the hormone is complexed with either two or three Fab fragments. The LH-Fab alpha complexes retain only about 13% receptor binding activity as compared to LH when measured in a radioligand receptor assay in which the radiolabeled ligand is human choriogonadotropin. (Use of the human hormone as labeled ligand permits direct measurement of competition between receptor and the bovine complex because the alpha portion of the human hormone does not cross react significantly with antibodies directed against bovine alpha subunits.) Complex formation does not lead to dissociation of the lutropin into its subunits, as shown with a homologous LH-beta immunoassay which distinguishes free beta subunit from intact LH. Complexing of LH with Fab-alpha fragments also causes little or no change in the affinity of the hormone's beta subunit for anti-LH-beta antibodies indicating that significant changes in beta subunit conformation did not occur. The data show that at least two well-separated antigenic regions on the alpha subunit are exposed to the surface in the intact hormone. They are also in agreement with the proposal that the loss of binding activity to receptor is due to steric effects rather than to changes in conformation or dissociation, and that there may be sites on the alpha subunit which interact directly with the receptor.     

Isolation of the receptor for Amaranthus Leucocarpus lectin from murine peritoneal macrophages

The receptor for Amaranthus leucocarpus lectin from CD-1 resident macrophages was purified with affinity chromatography with biotin labeled A. leucocarpus lectin and using avidin-agarose as affinity matrix. The receptor is a glycoprotein of 70 kDa that contains 18% of sugar by weight; it is mainly composed of galactose and N-acetyl D galactosamine in its saccharidic portion, and lacks sialic acid; the protein is rich in glycine, serine and alanine and lacks cysteine residues. The amino terminus of the receptor is blocked. By ionic strength chromatography on a mono P column in anionic form we purified three isoforms from the affinity purified receptor, each showing quantitative differences in glycosylation. The A. leucocarpus lectin receptor is identified only in resting, not activated, macrophages suggesting that it plays a role in activation mechanisms of macrophages     

Spin-Trapping and Chemiluminescence Studies of Neutrophils from a Holstein-Friesian Calf with Bovine Leukocyte Adhesion Deficiency

The ability of neutrophils from a Holstein-Friesian calf with bovine leukocyte adhesion deficiency (the proband with a genetic deficiency of the Mac-1 (CD11b/CD18) glycoprotein corresponding to the receptor of complement iC3b) to generate oxygen radicals was examined using electron spin resonance spectrometry (ESR) combined with a spin-trapping technique and luminol-dependent chemiluminescence spectrometry. When the neutrophils were stimulated with phorbol 12-myristate 13-acetate (PMA), an ESR spectrum confirming the generation of superoxide anions (O₂^?) was clearly observed in both healthy and diseased calves. However, when the neutrophils were stimulated by opsonized zymosan, appearance of the ESR spectrum was recognized in the healthy calves but not in the diseased calf. Similar results were obtained from chemiluminescence experiments.     

Microfibril-associated protein 4 is present in lung washings and binds to the collagen region of lung surfactant protein D.

We have purified a glycoprotein from bovine lung washings using affinity chromatography on a maltose-affinity column. On SDS-polyacrylamide gel electrophoresis the protein showed a molecular mass of 36 kDa in the reduced state and 66 kDa in the unreduced state. On gel permeation chromatography the apparent molecular mass was 250 kDa. N-terminal sequencing showed homology to the human matrix protein microfibril-associated protein (hMFAP4), and the glycoprotein was designated bovine MFAP4 (bMFAP4). Lung surfactant protein D (SP-D) was also purified from lung washings, and calcium-dependent binding was demonstrated between bMFAP4 and SP-D. hMFAP4 was cloned, and recombinant hMFAP4 showed the same binding pattern to SP-D as bMFAP4. No binding was seen to recombinant SP-D composed of the neck region and carbohydrate recognition domain of SP-D, indicating that the interaction between MFAP4 and SP-D is mediated via the collagen region of SP-D. MFAP4 also showed calcium-dependent binding to mannan, which was partially inhibited by maltose. Our findings indicate that MFAP4 has two binding specificities, one for collagen and one for carbohydrate, and we suggest that MFAP4 may fix the collectins in the extracellular compartment during inflammation.     

The plasma cell membrane glycoprotein, PC-1, is a threonine-specific protein kinase stimulated by acidic fibroblast growth factor.

A 32P-labeled protein that co-purified with acidic fibroblast growth factor (aFGF) receptor from bovine liver proved to be a distinct membrane protein, which itself has kinase activity that is stimulated by aFGF. The protein was designated MAFP for major aFGF-stimulated phosphoprotein. MAFP was purified from bovine liver using immunoaffinity chromatography with monoclonal antibody to MAFP following Triton X-100 extraction of plasma membranes and wheat germ lectin-Sepharose 4B column chromatography. The purified MAFP showed molecular masses of 130 kDa and 260 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions, respectively. Purified MAFP elicited aFGF-stimulated Thr-specific autophosphorylation activity and phosphorylation activity toward protein substrates (myelin basic protein and histone). Amino acid sequence analyses of 16 peptide fragments of MAFP, produced by endoproteinase Lys-C digestion followed by reduction and S-pyridylethylation, showed approximately 80-100% homology with the cDNA-deduced amino acid sequences of human and mouse plasma cell membrane glycoprotein, PC-1 (Buckley, M. F., Loveland, K. A., McKinstry, W. J., Garson, O. M., and Goding, J. W. (1990) J. Biol. Chem. 265, 17506-17511), suggesting that MAFP is the bovine version of PC-1. The amino acid sequences of bovine MAFP, human and mouse PC-1 reveal a putative ATP binding site in their extracellular domains. These results suggest that MAFP(PC-1) is an ectoprotein kinase. In addition to the kinase activity, MAFP(PC-1) was also found to possess alkaline nucleotide phosphodiesterase activity. It is now clear that several of the unique properties previously attributed to the aFGF receptor kinase are actually properties of this novel Thr-specific ectoprotein kinase, which co-purifies with the aFGF receptor and is responsive to stimulation by aFGF.     

Biochemical and immunological characterization of the major envelope glycoprotein of bovine leukemia virus.

The major envelope glycoprotein of bovine leukemia virus was isolated by lectin-bound Sepharose and DEAE-cellulose column chromatography. This protein was shown to have a molecular weight of about 41,000 and to lack detectable immunological cross-reactivity with glycoproteins of other oncornaviruses. Sera obtained from 100% of cattle examined with clinically diagnosed lymphosarcoma contained high-titered antibody to 125I-labeled bovine leukemia virus glycoprotein, whereas sera from animals in a disease-free herd were antibody negative.     

Characterization of protein S, a gamma-carboxyglutamic acid containing protein from bovine and human plasma.

Protein S is a vitamin K dependent protein of unknown function, which is present in mammalian plasma. It was isolated from bovine plasma by barium citrate adsorption and elution, ammonium sulfate fractionation, and column chromatography on DEAE-Sephadex, heparin-agarose, and polyhomoarginine-Sepharose. Bovine Protein S (Mr 64,200) is a single-chain glycoprotein with an amino-terminal sequence of Ala-Asn-Thr-Leu-Leu-. It contains 7.0% carbohydrate and 10 residues of gamma-carboxyglutamic acid per mol of protein. Human Protein S (Mr 69,000) is also a single-chain glycoprotein with an amino-terminal sequence of Ala-Asn-Ser-Leu-Leu-. It contains 7.8% carbohydrate and 10 residues of gamma-carboxyglutamic acid per mol of protein. These results indicate that Protein S from bovine or human plasma shows many similarities to the other vitamin K dependent proteins present in plasma.     

The nature of the microfibrillar glycoproteins of elastic fibres. A biosynthetic study.

1. Cell cultures propagated from foetal bovine ligamentum nuchae synthesized and secreted two glycoproteins, designated MFP I and MFP II, that are closely related to elastic-fibre microfibrils. Glycoproteins MFP I (apparent mol.wt. 150 000) and MFP II (apparent mol.wt. 300 000) were metabolically labelled, separated from other culture-medium components by immunoprecipitation with a specific anti-(microfibrillar protein) serum, and analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and sodium dodecyl sulphate/gel-filtration chromatography. 2. Ligament cells also synthesized and secreted fibronectin, but salt-fractionation and immunoprecipitation studies with a specific anti-(cold-insoluble globulin) serum established that neither glycoprotein MFP I nor glycoprotein MFP II was related to fibronectin. 3. The secretion of glycoprotein MFP I, but not that of glycoprotein MFP II, was enhanced by the addition of ascorbate to the culture medium. 4. Ascorbate-supplemented ligament cells incorporated [3H]proline into glycoprotein MFP I, and 36% of the nondiffusible proline residues were hydroxylated, exclusively as 4-hydroxy[3H]proline. Less than 1% of the total proline residues in [3H]proline-labelled glycoprotein MFP II were hydroxylated. 5. Ascorbate-supplemented cells incorporated [14C]lysine into glycoprotein MFP I and 30% of the non-diffusible lysine residues were hydroxylated. 6. Newly secreted glycoprotein MFP I was digested by highly purified bacterial collagenase to yield polypeptide fragments of apparent mol.wts. 50 000 and 30 000. Glycoprotein MFP II was not digested by bacterial collagenase. 7. The results suggest that elastic-fibre microfibrils are composed of a novel collagenous glycoprotein MFP I in association, as yet undefined, with a non-collagenous glycoprotein MFP II.     

Characterization of the oligosaccharide units of the bovine erythrocyte membrane glycoprotein.

The major glycoprotein of the bovine erythrocyte membrane was purified by extraction of the ghosts with lithium 3,5-diiodosalicylate followed by phenol-water extraction and acidification. The glycoprotein contains 20% protein and 80% carbohydrate by weight and gives a single band on sodium dodecyl sulfate-polyacrylamide gels with an estimated molecular weight of 230000 daltons. The carbohydrate composition of the glycoprotein was determined to be (in residues relative to sialic acid): sialic acid, 1.0; fucose, less than 0.01; mannose, 0.1; galactose, 3.3; N-acetylgalactosamine, 0.9; and N-acetylglucosamine, 2.4. Pronase digestion of the isolated glycoprotein followed by Sephadex G-75 gel filtration resulted in the separation of a small pool of glycopeptides (pool III), which included all of the mannose-containing glycopeptides, from the bulk of the glycopeptide material which was in the void fractions of the column (pool I). Alkaline borohydride treatment released over 95% of the oligosaccharide units in pool I and approximately 30% of the oligosaccharide units in pool III. These oligosaccharides were isolated by gel filtration and ion-exchange chromatography. The oligosaccharides released from pool I had molecular weights of 1100-1400 daltons and contained sialic acid, galactose, and N-acetylglucosamine in molar ratios of 0.5-1:3:2 as well as a partial residue of N-acetylgalactosaminitol. The oligosaccharides released from pool III by alkali had molecular weights of 1300-1600 daltons and contained sialic acid, galactose, N-acetylglucosamine, N-acetylgalactosamine and N-ACETYLgalactosaminitol in molar ratios of 1-2:2:1:1:1. These data indicate that the majority of the oligosaccharide units of the bovine erythrocyte glycoprotein are linked O-glycosidically to the peptide backbone of the molecule.     

The effect of bovine seminal plasma on the function and integrity of bovine neutrophils

Spermatozoa, by virtue of their high content of polyunsaturated fatty acids and limited antioxidant activity, are highly sensitive to lipid peroxidation. Sources of reactive oxygen species in the female genital tract include neutrophils recruited in response to insemination or those contained within the ejaculate, or even spermatozoa themselves. This study was undertaken to investigate the effect of seminal plasma of bulls on bovine neutrophils. Seminal plasma was removed from ejaculates of 6 healthy bulls by centrifugation. Neutrophils were isolated from jugular venous blood samples obtained from lactating Holstein cows. Seminal plasma was found to decrease measured Superoxide anion production by activated neutrophils (P = 0.008) in a concentration-dependent manner over the range tested (0 to 16%). This effect may reflect Superoxide scavenging by the seminal plasma or direct inhibition of the neutrophils. It has the potential physiological advantage of protecting spermatozoa from oxidative damage. Seminal plasma was found to reduce homotypic neutrophil aggregation dramatically (P < 0.0001). At a seminal plasma concentration of 0.2% neutrophil aggregation was virtually abolished. Homotypic neutrophil aggregation depends on the CD 11b/CD 18 (Mac-1) receptor, which also functions as the C3bi receptor (known as complement receptor-3 or CR3). If this receptor is down-regulated, the ability of neutrophils to phagocytose complement-opsonized microorganisms would be compromised. Finally, seminal plasma was found to increase neutrophil permeability to trypan blue in a concentration and time dependent fashion (P < 0.0001), indicating a direct cytotoxic effect. Taken together, these findings indicate a profound inhibition of neutrophil function by bovine seminal plasma. While these mechanisms are likely to protect spermatozoa from oxidative damage or phagocytosis, they also have the potential to diminish defense against pathogenic microorganisms.