Two novel phospholipid-linked mouse thymocyte surface molecules released by phosphatidylinositol-specific phospholipase C.
We searched for mouse thymocyte surface proteins attached to the cell membrane through a phosphatidylinositol (PI)-containing glycolipid similar to that identified in the T cell-activating Thy-1 glycoprotein. Our approach was to biochemically analyse the supernatants of 125I surface-labeled thymocytes treated with 60 U/ml of Staphylococcus aureus PI-specific phospholipase C (PI-PLC). In addition to Thy-1, two molecules of Mr 13,000 and 52,000 were found to be specifically solubilized by the enzymatic treatment. The 52,000 structure is a single basic polypeptide of Mr 50,000 under non-reducing conditions. Two-dimensional gel electrophoresis analyses resolved the 13,000 mol. wt molecules in three relatively basic components including (i) a monomeric molecule(s), a fraction of which exhibited slower migration in reducing gels, and (ii) disulfide-linked multimeric structures comprising a major component of Mr 30,000 and a minor one of Mr 45,000. These 52,000 and 13,000 mol. wt molecules could be released from thymocytes and Escherichia coli lipopolysaccharide (LPS)-stimulated B cell blasts, but not from a variety of mature T cell populations. These data add new members to the list of PI-linked rodent lymphoid cell differentiation markers, which already includes three activation signal-transducing T cell molecules (i.e. Thy-1, Ly-6-linked T cell-activating proteins, and RT-6).
D000818:Animals; D001402:B-Lymphocytes / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008815:Mice, Inbred Strains; D008970:Molecular Weight; D010716:Phosphatidylinositols / Q000378:metabolism*; D013601:T-Lymphocytes / Q000032:analysis* / Q000187:drug effects; D010738:Type C Phospholipases / Q000494:pharmacology*
D008565:Membrane Proteins; D010716:Phosphatidylinositols; D010738:Type C Phospholipases