The role of lipid rafts in T cell antigen receptor (TCR) signalling

Plasma membranes of many cell types contain domains enriched in specific li pids and cholesterol, called lipid rafts. In T lymphocytes, key T cell anti gen receptor (TCR) signalling molecules associate with rafts, and disruptin g raft-association of certain of these abrogates TCR signalling. The TCR it self associates with lipid rafts, and TCR crosslinking causes aggregation o f raft-associated proteins. Furthermore, raft aggregation promotes tyrosine phosphorylation and recruitment of signalling proteins, but excludes the t yrosine phosphatase CD45. Together the data suggest that lipid rafts are im portant in controlling appropriate protein interactions in resting and acti vated T cells, and that aggregation of rafts following receptor ligation ma y be a general mechanism for promoting immune cell signalling.