Fetal Membrane Collagens: Identification of Two New Collagen Alpha Chains

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 73; no. 8; pp. 2579 - 2583
• Main Authors: Burgeson, Robert E., El Adli, Fouad A., Kaitila, Ilkka I., Hollister, David W.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.08.1976; National Acad Sciences
• Subjects: Amino acids; Amino Acids - analysis; Amnion; Amnion - analysis; Biochemistry; Chemical precipitation; Chorion; Chorion - analysis; Collagen - analysis; Collagens; Electrophoresis; Electrophoresis, Polyacrylamide Gel; Extraembryonic Membranes - analysis; Female; Gels; Humans; Peptides - analysis; Pregnancy; Salts; Table salt
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.73.8.2579

Human fetal membranes contain two new genetically distinct collagen polypeptide chains which are subunits of one (or two) new molecular species of collagen. These new polypeptide chains, which we have tentatively named α A and α B, have been directly compared with the polypeptide chain subunits of Types I, II, and III human collagen and Type IV collagen from bovine lens capsule. Both α A and α B exhibit characteristic profiles on carboxymethyl-cellulose chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The distribution of methionine residues along both new chains is different from known collagen chains as manifest by distinctly different cyanogen bromide peptide profiles on carboxymethyl-cellulose chromatography and/or sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Both α A and α B exhibit contents of imino acids and glycine typical of collagens, and comparison with the observed and reported compositions of collagen chains of Types I-IV collagens reveals notable differences, particularly in the content of alanine, leucine, isoleucine, and the basic amino acids, lysine, hydroxylysine, and arginine. The new collagen species containing both α A and α B may be separated in the native (triple-helical) state from other native collagen species by differential salt precipitation. The observations that both chains coprecipitate in the same narrow NaCl range, and that the ratio of α A:α B is constant, suggest the possibility of a single new species of collagen with a subunit structure α A [α B]2.