MEMBRANE COMPARTMENTATION IS REQUIRED FOR EFFICIENT T-CELL ACTIVATION

The plasma membrane of mammalian cells contains detergent-resistant me mbrane rafts enriched in glycosphingolipids and cholesterol. Although several important signaling molecules have been found in such rafts, e vidence documenting a functional role for their localization has been scarce. Using a fractionation scheme that preserves tyrosine phosphory lation, we show that T cell activation leads to a striking compartment ation in the rafts of activated T cell receptor and associated signal- transducing molecules. Conditions that reversibly disrupt raft structu re either by dispersing their contents or by forcing their internaliza tion reversibly disrupt the earliest steps of T cell activation. Thus, raft integrity is a prerequisite for efficient T cell receptor signal transduction.