註釋 We investigated diffusive and distributive characteristics of membrane-bound species related to lipid rafts and involved in antigen-mediated mast cell activation in the allergic response as regulated by immunoglobulin-E (IgE) and its high affinity receptor FcepsilonRI. To evaluate this plasma membrane heterogeneity, we engineered two green fluorescent proteins (GFP) to target them to the plasma membrane inner leaflet in RBL-2H3 cells: (1) PM-EGFP is the GFP analogue to the Src-family tyrosine kinase Lyn; it incorporates sites for modification by saturated acyl anchors palmitate (16:0) and myristate (14:0); (2) For comparison, EGFP-GG, modeled after K-Ras and rap1B, is an inner leaflet probe anchored by an unsaturated geranylgeranyl (20:4) chain and an adjacent polybasic region. 