Release of Thy-1 from Human and Murine T-Cell Lines by a Specific Phospholipase

Abstract

Proteins on the outer surface of cultured human and murine lymphoblastoid T cells were labelled with ¹²⁵I. The labelled cells were incubated with the enzyme phosphatidylinositol-specific phospholipase C (PI-PLC). Proteins cleaved from the cell membrane by the enzyme were immunoprecipitated with anti-Thy-1 antibodies, separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and identified by autoradiography. A doublet of Thy-1 bands of approximately 16,000 daltons were detected. The result suggests that: (a) Thy-1 is present on the human and murine T cells which we tested, and (b) Thy-1 is attached to the cell membrane via a phosphatidylinositol domain.