The plasma membrane contains ordered lipid domains, commonly called lipid rafts,
enriched in cholesterol, sphingolipids, and certain signaling proteins. Lipid rafts play a
structural role in signal initiation by the high affinity receptor for IgE. Cross-linking of IgE-
receptor complexes by antigen causes their coalescence with lipid rafts, where they are
phosphorylated by the Src family tyrosine kinase, Lyn. To understand how lipid rafts
participate in functional coupling between Lyn and FcϵRI, we investigated whether the lipid …