title: Biochemical analysis of an MHC-linked hematopoietic cell surface antigen, Qa-2.
abstract: The region of the murine 17th chromosome telomeric to H-2D encodes a group of serologically defined cell surface antigens termed Qa-1-5. These antigens are of interest because their expression is restricted to hematopoietic cells. In addition, the molecular weight and subunit structure (ie, association with beta-2 microglobulin) of Qa-2 molecules are similar to H-2 and TL antigens. In the present studies, we have prepared isotopically labeled Qa-2 and H-2 molecules from mitogen-stimulated C57BL/6 spleen cells. Comparative peptide mapping of tryptic peptides from Qa-2 and H-2 molecules (Kb, DbKk, Dd) reveal that Qa-2 has a unique primary structure. However, considerable homology is indicated since 30--40% of the Qa-2 peptides cochromatograph with peptides derived from H-2Kb, H-2Db, H-2Kk, and H-2Dd. Studies by other investigators have demonstrated that similar levels of structural homology are observed when H-2K, H-2D, and H-2L tryptic peptides are analyzed. We conclude from these studies that the Qa-2 alloantigen is structurally related to a class of cell surface molecules (ie, H-2) that play critical roles in immune recognition processes. These data further suggest that the genes encoding Qa-2 and H-2 molecules have arisen from a common primordial gene.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000235:genetics* / Q000302:isolation & purification; D006410:Hematopoiesis; D015395:Histocompatibility Antigens Class I; D007519:Isoantigens / Q000302:isolation & purification; D008214:Lymphocytes / Q000276:immunology; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
chemical_list: D000954:Antigens, Surface; D015395:Histocompatibility Antigens Class I; D007519:Isoantigens; D010446:Peptide Fragments; C032907:Q surface antigens; D014357:Trypsin