Floating the raft hypothesis: the roles of lipid rafts in B cell antigen receptor function

The initiation of antibody responses to foreign antigens requires that B ce lls receive and integrate a variety of signals through an array of cell sur face receptors including the B cell antigen receptor (BCR) as well as a num ber of essential coreceptors. Recent evidence indicates that cholesterol-ri ch plasma membrane microdomains, referred to here as lipid rafts, serve as platforms for BCR signaling and trafficking in B cells. The existence of ra fts suggests a previously unappreciated level of organization at the B cell surface that may explain, at least in part, how BCR signaling is coordinat ed. Here the current evidence that lipid rafts play a key role in B cell re sponses is reviewed.