Binding and phosphorylation reactions in the model that occur both in raft and in nonraft compartments.

<p>1) Constitutive association of Lyn unique domain with the β subunit of the receptor. 2) Binding and cross-linking of IgE-FcεRI complexes by a multivalent ligand; 3) Transphosphorylation of the β and γ ITAMs by constitutively associated Lyn. 4) Recruitment of Lyn through its SH2 domain to the phosphorlated β ITAM and recruitment of Syk through its two SH2 domains to the doubly phosphorylated γ ITAM. 5) Michaelis-Menton interaction of a receptor aggregate containing Syk with LAT resulting in a phosphorylated LAT. 6) Binding of Grb2 to phosphorylated. Not shown are the reactions that dephosphorylate unprotected tyrosines.