SEARCH · PubMed Health

Results for “Collagen”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1979

Identification of organic phosphorus covalently bound to collagen and non-collagenous proteins of chicken-bone matrix. The presence of O-phosphoserine and O-phosphothreonine in non-collagenous proteins, and their absence from phosporylated collagen.

Non-collagenous phosphoproteins, almost all of which can be extracted in EDTA at neutral pH in the presence of proteinase inhibitors, are identified in the matrix of chicken bone, and are therefore not covalently bound to collagen. Similarly, all the peptides containing gamma-carboxyglutamic acid are present in the EDTA extract and none in the insoluble residue, confirming that none is covalently linked to chicken bone collagen. However, organic phosphorus is also found to be present in chicken bone collagen, principally in the alpha2-chains. Of the total protein-bound organic phosphorus present in chicken bone matrix, approx. 80% is associated with the non-collagenous proteins and 20% with collagen. The soluble non-collagenous proteins contain both O-phosphoserine and O-phosphothreonine and these account for essentially of their organic phosphorus content. In contrast, collagen contains neither O-phosphoserine nor O-phosphothreonine. Indeed, no phosphorylated hydroxy amino acid, phosphoamidated amino acid or phosphorylated sugar could be identified in purified components of collagen, which contain approximately four to five atoms of organic phosphorus per molecule of collagen. Peptides containing organic phosphorus were isolated from partial acid hydrolysates and enzymic digests of purified collagen components, which contain an as-yet-unidentified cationic amino acid. These data, the very high concentrations of glutamic acid in the phosphorylated peptides, and the pH-stability of the organic phosphorus moiety in intact collagen chains strongly suggest that at least part of the organic phosphorus in collagen is present as phosphorylated glutamic acid. This would indicate that the two major chemically different protein fractions in chicken bone matrix that contain organic phosphorus may represent two distinct metabolic pools of organic phosphorus under separate biological control.

1-Carboxyglutamic Acid↗

PubMed1992

The fibrillar collagens, collagen VIII, collagen X and the C1q complement proteins share a similar domain in their C-terminal non-collagenous regions.

A sequence comparison of the C-termini of collagens X, VIII, the collagen-like complement factor C1q, and the fibrillar collagens showed a conserved cluster of aromatic residues. This conserved cluster was in a domain of approximately 130 amino acids that exhibited marked similarities in hydrophilicity profiles between the different collagens, despite a low level of sequence similarity. These data suggest that the 'collagen X-like family' and the fibrillar collagens contain a domain within their C-termini that adopts a common tertiary structure, and that a conserved cluster of aromatic residues in this domain may be involved in C-terminal trimerization.

Amino Acid Sequence↗

PubMed1989

The cloning and sequencing of alpha 1(VIII) collagen cDNAs demonstrate that type VIII collagen is a short chain collagen and contains triple-helical and carboxyl-terminal non-triple-helical domains similar to those of type X collagen.

We have isolated two overlapping cDNA clones covering 2425 base pairs encoding a short type VIII collagen chain synthesized by rabbit corneal endothelial cells. The cDNAs encode an open reading frame of 744 amino acid residues containing a triple-helical domain of 454 residues flanked by 117- and 173-residue amino and carboxyl non-triple-helical domains (called NC2 and NC1, respectively). Based on the identity between the DNA-derived amino acid sequence and the amino acid sequence of a type VIII collagen CNBr peptide obtained from rabbit corneal Descemet's membrane, we conclude that the cDNAs code for a type VIII collagen chain. We give this chain the designation alpha 1(VIII). The alpha 1(VIII) triple-helical domain contains eight imperfections in the Gly-X-Y repeated structure with Gly-X instead of a full triplet. The length of the triple-helical domain and number and relative locations of these imperfections are remarkably similar to those of chicken alpha 1(X) collagen. The amino acid sequence of the carboxyl three-quarters of the NC1 domain has high sequence similarity to that of alpha 1(X) collagen. These data suggest that the triple-helix coding portions and carboxyl three-quarters of the NC1 domains of the alpha 1(VIII) and alpha 1(X) genes have a common evolutionary origin.

Amino Acid Sequence↗

PubMed1990

A 48 kDa collagen-binding phosphoprotein isolated from bovine aortic endothelial cells interacts with the collagenous domain, but not the globular domain, of collagen type IV.

We have identified collagen-binding proteins in detergent extracts of metabolically labelled bovine aortic endothelial cells (BAEC) by collagen type IV-Sepharose affinity chromatography. The major collagen type IV-binding protein identified by SDS/PAGE had a molecular mass of 48 kDa, which we term the 'collagen-binding 48 kDa protein' (CB48). The pI of CB48 was 8.0-8.3 in a two-dimensional gel system, running non-equilibrium pH gel electrophoresis in the first dimension and SDS/PAGE in the second dimension. Under these conditions CB48 separated into two major (a and b) and one minor isoform (c); a was the most basic of the three isoforms. Two-dimensional chymotryptic peptide maps derived from each individual isoform were virtually identical. The charge differences between the isoforms were due in part to differential H3(32)PO4 incorporation by the protein. CB48 bound to intact collagen type IV and the collagenous region of collagen type IV, but not to the globular NC1 domain. Cell-surface labelling and indirect immunofluorescence experiments localized the bulk of CB48 intracellularly in the endoplasmic reticulum Golgi region, with a minor population of molecules on the cell surface. A specific rabbit polyclonal anti-CB48 serum did not inhibit the attachment or spreading of BAEC to collagen type IV in an 'in vitro' adhesion assay, suggesting that the cell-surface population of CB48 is not involved in BAEC adhesion. We conclude that CB48 is a collagen-binding phosphoprotein that interacts with the collagenous domain of collagen type IV and may be involved in intracellular transport of collagen molecules.

Animals↗

PubMed1991

Copolymerization of pNcollagen III and collagen I. pNcollagen III decreases the rate of incorporation of collagen I into fibrils, the amount of collagen I incorporated, and the diameter of the fibrils formed.

Previous observations suggested that pNcollagen III, the partially processed form of type III procollagen, coats fibrils of collagen I and thereby helps regulate the diameter of fibrils formed by collagen I. The previous observations, however, did not exclude the possibility that pNcollagen III was deposited on preformed collagen I fibrils after the fibrils were assembled. Here, mixtures of pNcollagen III and collagen I were generated simultaneously by enzymatic cleavage of precursor forms of the proteins. The results demonstrated that pNcollagen III forms true copolymers with collagen I. The presence of pNcollagen III both inhibited the rate at which collagen I assembled into fibrils and decreased the amount of collagen I incorporated into fibrils at steady-state equilibrium. In addition, the results demonstrated that copolymerization of pNcollagen III with collagen I generated fibrils that were thinner than fibrils generated under the same conditions from collagen I alone. Increasing the initial molar ratio of pNcollagen III to collagen I in the solution-phase increased the amount of pNcollagen III copolymerizing with collagen I and progressively decreased the diameter of the fibrils. Therefore, the copolymers were heterogeneous in that the stoichiometry of the two monomers in the fibrils varied. The results are consistent with a model in which pNcollagen III can regulate the diameter of collagen I fibrils by coating the surface of the fibrils and thereby allow tip growth but not lateral growth of the fibrils.

Collagen↗

PubMed1990

The attachment and growth of an established cell line on collagen, chemically modified collagen, and collagen composite surfaces.

The attachment and growth of an established cell line derived from mouse fibroblasts on collagen, chemically modified collagen, and collagen composite surfaces were compared. Tissue culture polystyrene dishes provided a suitable control. The substrates included native bovine dermal collagen, succinylated, acetylated and methylated collagen, and a series of composite materials formed from collagen and the glycosaminoglycans hyaluronic acid, chondroitin 4-sulphate and chondroitin 6-sulphate and the glycoprotein fibronectin. Attachment and growth of cells on each of these substrates were assessed by visual inspection under optical microscopy, by detachment of the cells using trypsinization and subsequent counting in a Coulter counter; and by 3H-thymidine incorporation studies. A very good correlation between the results was obtained by the three methods employed which showed that collagen, in comparison to polystyrene, is a relatively poor substrate for cellular attachment, growth and proliferation, but it may be improved by chemical modification and by incorporation of either fibronectin, chondroitin sulphate (5 and 10%), or low levels (less than 5%) of hyaluronic acid into the collagen matrix. Concentrations in excess of 5% hyaluronic acid into the collagen matrix, however, appeared to inhibit cellular attachment and growth and such materials provided a poorer substrate than native collagen.

Animals↗

PubMed1977

Effect of cortisol acetate on collagen biosynthesis and on the activities of prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase and collagen glucosyltransferase in chick-embryo tendon cells.

Collagen synthesis and the activities of prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase and collagen glucosyltransferase were studied in isolated chick-embryo tendon cells after the administration of cortisol acetate to the chick embryos. When the steroid was injected 1 day before isolation of the tendon cells, collagen synthesis was decreased, even though the enzyme activities were not changed. When cortisol acetate was given as repeated injections over a period of 4 days, both collagen synthesis and the enzyme activities decreased. The hydroxylase activities decreased even more than the two collagen glycosyltransferase activities, both in isolated cells and in whole chick embryos. The amount of prolyl hydroxylase protein diminished to the same extent as the enzyme activity, indicating that cortisol acetate inhibits enzyme synthesis. The inhibitory effect of cortisol acetate on collagen synthesis and on the enzyme activities was partially reversible in 3 days. Total protein synthesis was completely restored within this time. Only massive doses of cortisol acetate inhibited collagen synthesis in vitro. Additional experiments indicated that cortisol acetate did not decrease the rate of the enzyme reactions when added directly to the enzyme incubation mixtures. The results suggest that cortisol acetate decreases collagen synthesis both by its direct effect on collagen polypeptide-chain synthesis and by decreasing the activities of enzymes involved in post-translational modifications.

Animals↗

PubMed1991

The complete primary structure of type XII collagen shows a chimeric molecule with reiterated fibronectin type III motifs, von Willebrand factor A motifs, a domain homologous to a noncollagenous region of type IX collagen, and short collagenous domains with an Arg-Gly-Asp site.

Extracellular matrix molecules are generally categorized as collagens, elastin, proteoglycans, or other noncollagenous structural/cell interaction proteins. Many of these extracellular proteins contain distinctive repetitive modules, which can sometimes be found in other proteins. We describe the complete primary structure of an alpha 1 chain of type XII collagen from chick embryonic fibroblasts. This large, structurally chimeric molecule identified by cDNA analysis combines previously unrelated molecular domains into a single large protein 3,124 residues long (approximately 340 kD). The deduced chicken type XII collagen sequence starts at the amino terminus with one unit of the type III motif of fibronectin, which is followed by one unit homologous to the von Willebrand factor A domain, then one more fibronectin type III module, a second A domain from von Willebrand factor, 6 units of type III motif and a third A domain, 10 consecutive units of type III motif and a fourth A domain, a domain homologous to the NC4 domain peptide of type IX collagen, and finally two short collagenous regions previously described as part of the partially sequenced collagen type XII molecule; an Arg-Gly-Asp potential cell adhesive recognition sequence is present in a hydrophilic region at the terminus of one collagenous domain. Antibodies raised to type XII collagen synthesized in a bacterial expression system recognized not only previously reported bands (220 kD et cetera) in tendons, but also bands with apparently different molecular sizes in fibroblasts and 4-d embryos. The antibodies stained a wide variety of extracellular matrices in embryos in patterns distinct from those of fibronectin or interstitial collagens. They prominently stained extracellular matrix associated with certain neuronal tissues, such as axons from dorsal root ganglia and neural tube. These studies identify a novel chimeric type of molecule that contains both adhesion molecule and collagen motifs in one protein. Its structure blurs current classification schemes for extracellular proteins and underscores the potentially large diversity possible in these molecules.

Amino Acid Sequence↗

PubMed1976

Digestion of native collagen, denatured collagen, and collagen fragments by extracts of rat liver lysosomes.

Extracts of highly purified lysosomes from rat liver were examined for their ability to degrade native collagen and thermally denatured collagen at pH values between 3.5 and 7.0. After a 24-h digestion at 36 degrees with the lysosomal extract at a pH of 5.5 or lower (collagen/lysosomal protein; 2/1 or 8/1), both native and denatured collagen were degraded to an extent equivalent to 60 to 70% of that observed upon total acid hydrolysis in 6 N HCl as measured by the ninhydrin reaction (570 nm). At a pH of 6.0, native collagen and denatured collagen were degraded by the mixture of lysosomal proteinases to 11% and 40% of total acid hydrolysis, respectively. At pH 6.5 AND 7.0, the corresponding values were 3% versus 33% and 0.3% versus 11%, respectively. Fragments of collagen (TCA and TCB) are produced when mammalian collagenase degrades native collagen at 25 degrees. These fragments were degraded by the lysosomal extract at 36 degrees to an extent equivalent to 28% and 8% of total acid hydrolysis at pH 6.5 and 7.0, respectively. The experiments at pH 6.5 and 7.0 were done using a collagen/lysosomal protein ratio of 2/1. At pH 5.0 (a pH which is found within secondary lysosomes), the lysosomal extracts degraded collagen to a mixture of free amino acids and small peptides. Amino acid analysis established that approximately 30% of the amino acid residues of the collagen appeared in the lysosomal hydrolysate as free amino acids. Hydroxyproline and perhaps hydroxylysine were the only amino acids found in collagen which did not appear at least to some extent as the free amino acid in this hydrolysate.

Amino Acids↗

PubMed1975

Studies on the glycosylation of hydroxylysine residues during collagen biosynthesis and the subcellular localization of collagen galactosyltransferase and collagen glucosyltransferase in tendon and cartilage cells.

1. The glycosylation of hydroxylysine during the biosynthesis of procollagen by embryonic chick tendon and cartilage cells was examined. When free and membrane-bound ribosomes isolated from cells labelled for 4min with [(14)C]lysine were assayed for hydroxy[(14)C]lysine and hydroxy[(14)C]lysine glycosides, it was found that hydroxylation took place only on membrane-bound ribosomes and that some synthesis of galactosylhydroxy[(14)C]lysine and glucosylgalactosylhydroxy[(14)C]lysine had occurred on the nascent peptides. 2. Assays of subcellular fractions isolated from tendon and cartilage cells labelled for 2h with [(14)C]lysine demonstrated that the glycosylation of procollagen polypeptides began in the rough endoplasmic reticulum. (14)C-labelled polypeptides present in the smooth endoplasmic reticulum and Golgi fractions were glycosylated to extents almost identical with the respective secreted procollagens. 3. Assays specific for collagen galactosyltransferase and collagen glucosyltransferase are described, using as substrate chemically treated bovine anterior-lens-capsule collagen. 4. When homogenates were assayed for the collagen glycosyltransferase activities, addition of Triton X-100 (0.01%, w/v) was found to stimulate enzyme activities by up to 45%, suggesting that the enzymes were probably membrane-bound. 5. Assays of subcellular fractions obtained by differential centrifugation for collagen galactosyltransferase activity indicated the specific activity to be highest in the microsomal fractions. Similar results were obtained for collagen glucosyltransferase activity. 6. When submicrosomal fractions obtained by discontinuous-sucrose-density-gradient-centrifugation procedures were assayed for these enzymic activities, the collagen galactosyltransferase was found to be distributed in the approximate ratio 7:3 between rough and smooth endoplasmic reticulum of both cell types. Similar determinations of collagen glucosyltransferase indicated a distribution in the approximate ratio 3:2 between rough and smooth microsomal fractions. 7. Assays of subcellular fractions for the plasma-membrane marker 5'-nucleotidase revealed a distribution markedly different from the distributions obtained for the collagen glycosyltransferase. 8. The studies described here demonstrate that glycosylation occurs early in the intracellular processing of procollagen polypeptides rather than at the plasma membrane, as was previously suggested.

Animals↗

PubMed1989

The interaction of fibronectin (fn) with native, polymeric collagen (collagen fibres): comparison with von Willebrand factor (vWf)-binding by collagen.

The binding of fn to collagen (type I) fibres has been found to resemble that of vWf in the following respects: Binding is rapid, specific, saturable, similar at 4 and 37 degrees C, and reduced by increasing ionic strength. Binding is not inhibited by native, monomeric collagen, suggesting a multivalent mechanism of interaction. Binding of fn occurs to a variety of collagen fragments (after their renaturation and polymerization), including, for example, the collagenase-derived TCA and TCB 3/4 and 1/4 molecular fragments and the peptides alpha 1(I)CB3, 6b, 7 and 8 obtained by cleavage with cyanogen bromide (CB), suggesting a wide distribution of binding sites on the native collagen molecule. As judged by the effect of heat-treatment, the native conformation of fn is required. Chemical modification indicates the involvement of arginyl residues in collagen and carboxyl groups in fn. However, fn and vWf did not compete with one another in binding to collagen, suggesting the participation of different collagen arginyl residues in the two interactions. Fn-binding differed from that of vWf in that the former was inhibited by denatured monomeric collagen (gelatin). Fn-binding was also inhibited by the fragment TCA in denatured form. The inhibitory activity was lost after chemical modification of arginyl residues in gelatin. Our results suggest that fn binding to collagen fibres and gelatin involves the same widely-distributed spectrum of binding sites.

Amino Acids↗

PubMed1991

Age-related changes in collagen synthesis and degradation in rat tissues. Importance of degradation of newly synthesized collagen in regulating collagen production.

During developmental growth, collagens are believed to be continuously deposited into an extracellular matrix which is increasingly stabilized by the formation of covalent cross-links throughout life. However, the age-related changes in rates of synthetic and degradative processes are less well understood. In the present study we measured rates of collagen synthesis in vivo using a flooding dose of unlabelled proline given with [14C]proline and determining production of hydroxy[14C]proline. Degradation of newly synthesized collagen was estimated from the amount of free hydroxy [14C]proline in tissues 30 min after injection. Collagen fractional synthesis rates ranged from about 5%/day in skeletal muscle to 20%/day in hearts of rats aged 1 month. At 15 months of age, collagen fractional synthesis rates had decreased markedly in lung and skin, but in skeletal muscle and heart, rates were unchanged. At 24 months of age, synthesis rates had decreased by at least 10-fold in all tissues, compared with rates at 1 month. The proportion of newly synthesized collagen degraded ranged from 6.4 +/- 0.4% in skin to 61.6 +/- 5.0% in heart at 1 month of age. During aging the proportion degraded increased in all tissues to maximal values at 15 months, ranging from 56 +/- 7% in skin to 96 +/- 1% in heart. These data suggest that there are marked age-related changes in rates of collagen metabolism. They also indicate that synthesis is active even in old animals, where the bulk of collagens produced are destined to be degraded.

Aging↗

PubMed1992

Molecular cloning and partial characterization of a novel collagen chain, alpha 1(XVI), consisting of repetitive collagenous domains and cysteine-containing non-collagenous segments.

In an effort to identify new members of the collagen family, we screened a human placenta cDNA library with a collagenous probe. A novel 3.7 kb cDNA was identified encoding an open reading frame of 1,186 amino acids and containing a termination codon. The predicted polypeptide consists of 9 repetitive collagenous (stretches of Gly-X-Y) and several non-collagenous segments. Two cysteinyl residues separated by two amino acid residues (Cys-X-X-Cys) are regularly located in the N-terminal region of each non-collagenous segment. The deduced amino acid sequence described above is distinct from those of known types of collagen. Therefore, this novel collagen chain is designated alpha 1(XVI). Northern blot analysis revealed an alpha 1(XVI) mRNA of 5.2 kb, indicating that the overlapping cDNA clones isolated in this study covered nearly three-fourths of the mRNA. As a tool for further study on the expression of type XVI collagen, we prepared an antibody against the nonadecapeptide CFLSLERPRAEEARGDNSE, derived from the putative translation product of the cDNA. In immunoblot analysis, the antibody recognized a 160 kDa protein, which was bacterial collagenase-sensitive. Immunohistochemical stainings of human placental tissues with anti-peptide antibody revealed a positive reaction with amnion, the membranous tissue lining the amniotic cavity. The gene of alpha 1(XVI) chain, COL16A1, is mapped on the short arm of human chromosome 1 (1p13-p34).

Amino Acid Sequence↗

PubMed1992

Relationship of serum levels of pro-type I collagen peptide, pro-type III collagen peptide and type IV 7S collagen with cervical maturation.

The serum levels of pro-type I collagen peptide (PIP), pro-type III collagen peptide (PIIIP) and type IV 7S collagen (7S collagen) were measured in 41 women in various gestational weeks of pregnancy (5-41 weeks). The PIP level did not change during pregnancy, being 450 +/- 380 mg/ml before week 37 and 448 +/- 280 mg/ml after week 37. The PIIIP level also did not change being 0.55 +/- 0.21 and 0.59 +/- 0.22 U/ml before and after 37 weeks. The PIIIP level increased slightly but not significantly after week 37. The 7S collagen level, however, increased significantly (p less than 0.01), being 5.1 +/- 0.8 and 6.6 +/- 0.8 mg/ml before and after week 37. The correlation coefficients with the Bishop score were 0.22 for PIP, 0.42 for PIIIP, and 0.72 for 7S collagen. These data suggest that serum 7S collagen closely reflects collagen degradation in the cervix and so should be a good marker of cervical maturation.

Cervix Uteri↗

PubMed1991

Human bone contains type III collagen, type VI collagen, and fibrillin: type III collagen is present on specific fibers that may mediate attachment of tendons, ligaments, and periosteum to calcified bone cortex.

We evaluated the distribution of Type III collagen, Type VI collagen, and fibrillin in human bone, using monoclonal antibodies (MAb) of proven specificity. All three molecules are present in developing and remodeling bone. Type III collagen is present in discrete fiber bundles throughout the bone cortex but is concentrated at the Haversian canal surface and in the fibers at the bone-periosteal interface. The collagen fibrils in these bundles are of uniform diameter. Type III-containing collagen fibers are detected at all ages examined, from 30 fetal weeks to 80 years. Type VI collagen is present in fetal bone in discrete fibrils separate from Type III collagen, and becomes restricted to the margins of bone cells and the bone surface by 7 years. The distribution of fibrillin resembles that of Type III collagen in the fetus, but at 7 years is absent from the interior of the cortex except for the canaliculi and cement lines, and remains concentrated in discrete fibers at the bone surface.

Adult↗

PubMed1976

Intracellular enzymes of collagen biosynthesis in rat liver as a function of age and in hepatic injury induced by dimethylnitrosamine. Changes in prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase and collagen glucosyltransferase activities.

The relationship between the changes in the four enzyme activities catalysing intracellular post-translational modifications in collagen biosynthesis were studied in rat liver as a function of age and in experimental hepatic injury induced by the administration of dimethylnitrosamine. During aging, relatively large changes were found in prolyl hydroxylase and lysyl hydroxylase activities, whereas only minor changes took place in collagen galactosyltransferase and collagen glucosyltransferase activities. In hepatic injury, the two hydroxylase activities increased earlier and to a larger extent than did the two glycosyltransferase activities, and the largest was found in lysyl hydroxylase activity. The data support previous suggestions that changes in the rate of collagen biosynthesis in the liver cannot be explained simply by a change in the number of collagen-producing cells, but regulation of the enzyme activities existed, so that the two hydroxylase activities altered considerably more than did the two collagen glycosyltransferase activities.

Age Factors↗

PubMed1989

Expression of type II and type XI collagens in canine mammary mixed tumors and demonstration of collagen production by tumor cells in collagen gel culture.

The development of cartilaginous collagen types, II and XI, in canine mammary mixed tumors was studied biochemically and immunohistochemically. In mixed tumor, an alcian blue-positive myxomatous region appeared in the stroma, where round-shaped proliferating myoepithelial cells were scattered. Type II collagen was distributed in metaplastic cartilage matrix, while type XI was located only in the pericellular region, where proliferating cells were positively stained with anti-actin and anti-keratin antibodies. The accumulation of collagen types II and XI in the tumor mass was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting of the extract of the lesion using type-specific antibodies to collagen types II and XI. Tumor cells isolated from metaplastic tumor mass expressed both collagen types II and XI and myoepithelial types of cytoskeleton in gel culture, in which an alcian blue-positive substance became detectable in the pericellular region on day 3 and type II and type XI collagens on day 5. This may be a useful model for studying chondrocyte-type gene expression during tumorigenesis.

Animals↗

PubMed1992

Occurrence of collagen and proteoglycan forms of type IX collagen in chick embryo cartilage. Production and characterization of a collagen form-specific antibody.

Type IX collagen from chick embryonic cartilage is a proteoglycan bearing a single chondroitin sulfate chain covalently linked to the alpha 2(IX) polypeptide chain. We have isolated type IX collagen metabolically labeled with [3H]proline using an antibody to type IX collagen and have found that the molecule is synthesized in two forms, a collagen form (COLIX) and a proteoglycan form (PGIX). In cultured chondrocytes, the two forms of type IX collagen showed a different ability to be deposited in the matrix. We have suggested the possibility that both forms may arise from an alternative substitution of a chondroitin sulfate chain to the NC3 domain of the alpha 2(IX) chain. Based on the reported amino acid sequence at the NC3 domain of alpha 2(IX), we have synthesized undecapeptides containing the sequence around the glycosaminoglycan attachment site of the alpha 2(IX) chain. Antibody against the peptide, which was raised in rabbit, only recognized COLIX and made it possible to distinguish COLIX from PGIX. Evidence shows that this could be due to a difference in antigenicity of the NC3 domain of the alpha 2(IX) chain between COLIX and PGIX caused by the substitution of a chondroitin sulfate chain to the serine residue in this domain. Therefore, this antibody may be useful as a probe for studies on the functions of glycosaminoglycan substitution in type IX collagen.

Amino Acid Sequence↗