title: Expression of structurally diverse Qa-2-encoded molecules on the surface of cloned cytotoxic T lymphocytes.
abstract: Extracts of 125I-labeled cloned murine cytotoxic T lymphocytes (CTL) were immunoprecipitated with alloantisera to the cloned CTL and rabbit antisera to beta-2 microglobulin. Polyacrylamide gel electrophoresis (PAGE) of the specific precipitates revealed, as expected, 125I-labeled components that corresponded to products of class I genes of the major histocompatibility complex (MHC). However, additional class I gene products of relatively low apparent molecular weight (Mr) were also observed. Similar analyses of spleen cells from a variety of MHC-congenic mouse strains suggested that the class I molecules of relatively low Mr are encoded in the Qa-2 region of the MHC, and this was confirmed by immunoprecipitation with a monoclonal antibody to Qa-2. Surprisingly, however, the cell surface Qa-2 molecules of different CTL clones differed in Mr, in isoelectric focusing (IEF) pattern, and in the number of distinguishable molecules expressed per clone: some clones seemed to express only a single Qa-2-encoded molecule while others expressed two distinct ones. Treatment of the immunoprecipitated Qa-2 with endoglycosidase F (Endo F) resulted in a decrease in Mr of approximately 5,000-6,000, corresponding to the expected loss of N-linked oligosaccharides, but the decrease did not eliminate structural variability among the clones. Structural diversity of the Qa-2-encoded molecules expressed on CTL could arise because CTL clones differ (a) in the particular Qa-2 genes they express, (b) in the way they splice Qa-2 gene transcripts or, perhaps, (c) in Endo F-resistant oligosaccharides on their Qa-2 molecules.
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D000954:Antigens, Surface / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D002999:Clone Cells / Q000276:immunology; D005796:Genes; D005815:Genetic Code; D006183:H-2 Antigens / Q000235:genetics; D015395:Histocompatibility Antigens Class I; D007525:Isoelectric Focusing; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D011233:Precipitin Tests; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014018:Tissue Distribution
chemical_list: D000954:Antigens, Surface; D006183:H-2 Antigens; D015395:Histocompatibility Antigens Class I; C032907:Q surface antigens