The human invariant chain is the core protein of the human class II-associated proteoglycan

• Published in: The Journal of experimental medicine Vol. 164; no. 5; pp. 1422 - 1439
• Main Authors: GIACOLETTO, K. S, SANT, A. J, BONO, C, GORKA, J, O'SULLIVAN, D. M, QUARANTA, V, SCHWARTZ, B. D
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.11.1986; The Rockefeller University Press
• Subjects: Antigens; Antigens, Differentiation, B-Lymphocyte; Biological and medical sciences; Chondroitin Sulfate Proteoglycans - analysis; Chondroitin Sulfate Proteoglycans - immunology; Chondroitin Sulfate Proteoglycans - physiology; Chondroitinases and Chondroitin Lyases - pharmacology; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Histocompatibility antigens (hla, h-2 and other systems); Histocompatibility Antigens Class II - analysis; Humans; Methionine - metabolism; Molecular immunology; Molecular Weight; Proteoglycans - analysis; Solubility; Antigen; Human; Proteoglycan; HLA-System; Major histocompatibility system; Molecular association; Cell surface
• ISSN: 0022-1007; 1540-9538
• DOI: 10.1084/jem.164.5.1422

The human class II-associated chondroitin sulfate proteoglycan (CSPG) was analyzed biochemically and immunologically to determine a possible relationship with the human invariant chain (gamma 1) and its related components. The CSPG was purified by a three-step procedure involving associative ion-exchange chromatography, immunoprecipitation, and dissociative ion-exchange chromatography. Treatment of the CSPG with chondroitinase revealed core proteins of Mr approximately 46,000, 38,000, and 28,000, with the 38,000 species most highly represented. Tryptic peptide analysis revealed identity of the peptides of the 38,000 Mr core protein and gamma 1, and of the 28,000 Mr species and p25. The CSPG and its core proteins were shown to react directly with the mouse anti-human invariant chain monoclonal antibody VIC-Y1 and a rabbit antiserum produced against a synthetic peptide corresponding to the C-terminal end of invariant chain. These results demonstrate that the invariant chain is the core protein of the class II-associated CSPG. In addition, virtually all the CSPG was shown to be present on the cell surface.