title: Qa gene expression: biosynthesis and secretion of Qa-2 molecules in activated T cells.
abstract: The biosynthesis and expression of the tissue-specific class I molecule Qa-2 have been studied in resting and activated T-cell populations. Polyclonal activation of T lymphocytes induces a 3- to 4-fold increase in the biosynthesis of Qa-2 molecules but no increase in cell-surface levels. Analysis of the biosynthetic pathway of the Qa-2 molecule in activated lymphocytes reveals that approximately equal to 70% of the newly synthesized Qa-2 molecules are secreted as soluble molecules. In resting-cell populations, Qa-2 remains entirely cell-associated. This process is unique to the Qa-2 molecule, since other class I molecules (e.g., H-2Kb and H-2Db) synthesized by activated cells remain cell-associated. The possibility that the secreted Qa-2 molecule is the product of a new Qa gene or an alternatively spliced mRNA is considered. These results indicate that the Qa-2 molecules may not just function as a cell-surface recognition structure but also may serve a role as a soluble factor synthesized by activated lymphoid cell populations.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis* / Q000276:immunology / Q000502:physiology; D006183:H-2 Antigens / Q000235:genetics; D015395:Histocompatibility Antigens Class I; D007106:Immune Sera / Q000276:immunology; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D000954:Antigens, Surface; D006183:H-2 Antigens; D015395:Histocompatibility Antigens Class I; D007106:Immune Sera; C032907:Q surface antigens