title: Molecular weight and charge heterogeneity of Thy-1 glycoprotein in different populations of T-cells.
abstract: Molecular weight and charge microheterogeneity of Thy-1 glycoprotein expressed on different T-cell populations were compared by two-dimensional gel electrophoresis and endoglycosidase treatment. Thy-1 was immunoprecipitated from detergent lysates of radioiodinated T-cells of spleens, lymph nodes, Peyer's patches, peripheral blood, IL-2-cultured thymocytes and peanut agglutinin (PNA) separated thymocytes. In general, thymocytes and IL-2-cultured thymocytes expressed the highest levels of Thy-1 with a large Mr and charge variation. The Thy-1 of these cells was basic and contained low levels of sialic acid. On the other hand, peripheral T-lymphocytes exhibited a restricted Mr and more limited charge heterogeneity with higher amounts of sialic acid. The Thy-1 glycoprotein of mature, low Thy-1 PNA- thymocytes had Mr and charge heterogeneity identical to peripheral T-lymphocytes. The Mr and charge variation of immature PNA+ thymocytes was essentially identical to that of whole thymocytes. The molecular source of Mr heterogeneity in thymocyte Thy-1 and restricted Mr in lymph node Thy-1 was studied by analysis with endoglycosidase-H (Endo-H) and Endo-D. The results of Endo-H digestion showed that most of the Thy-1 polypeptides from both thymocyte and lymph node contained one high-mannose type oligosaccharide which was relatively small and not heterogeneous with respect to Mr. The complex-type oligosaccharides (Endo-D-sensitive) were larger and were responsible for the broad Mr-heterogeneity found in thymocyte Thy-1. Both thymocyte and lymph node Thy-1 generally appear to contain three N-linked oligosaccharides (one high-mannose and two complex) and sequential hydrolysis with Endo-H and Endo-D resulted in an unglycosylated polypeptide with an Mr of approx. 12,500.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000276:immunology; D002478:Cells, Cultured; D011232:Chemical Precipitation; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D006026:Glycoside Hydrolases; D051379:Mice; D008809:Mice, Inbred C3H; D008970:Molecular Weight; D019158:N-Acetylneuraminic Acid; D010446:Peptide Fragments / Q000032:analysis; D011817:Rabbits; D012794:Sialic Acids / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology*; D018800:Thy-1 Antigens
chemical_list: D000954:Antigens, Surface; D010446:Peptide Fragments; D012794:Sialic Acids; D018800:Thy-1 Antigens; D006026:Glycoside Hydrolases; D019158:N-Acetylneuraminic Acid