The Thy-1 antigen exhibits rapid lateral diffusion in the plasma membrane of rodent lymphoid cells and fibroblasts.
Thy-1 is a plasma membrane protein, but its primary structure lacks the typical membrane-spanning sequence. Recent studies revealed that a glycophospholipid is covalently bound to the carboxyl terminus, suggesting that the protein is integrated into the plasma membrane by this lipid moiety. Lateral diffusion of Thy-1 was measured in mouse thymocytes, lymphoma cells, and fibroblasts by the fluorescence recovery after photobleaching technique. Thy-1 was labeled with rhodamine-conjugated anti-Thy-1 monoclonal antibodies. Diffusion coefficients of 2-4 X 10(-9) cm2/sec were obtained for the antigen-antibody complex in all the cell types. About 50% of the Thy-1 was mobile. The diffusion coefficient for the mobile fraction of Thy-1 is considerably larger than the diffusion coefficients of many other plasma membrane proteins. Rather, the diffusion coefficient of Thy-1 is similar to those of lipid analogs embedded in the same membrane, providing strong support for the suggested lipid anchoring of this antigen.
D000818:Animals; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D002478:Cells, Cultured; D004058:Diffusion; D005347:Fibroblasts / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology*; D008223:Lymphoma / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D018800:Thy-1 Antigens
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D018800:Thy-1 Antigens