DEVELOPMENT OF A RAPID APPROACH TO IDENTIFICATION OF TYROSINE PHOSPHORYLATION SITES - APPLICATION TO PKC-DELTA PHOSPHORYLATED UPON ACTIVATION OF THE HIGH-AFFINITY RECEPTOR FOR IGE IN RAT BASOPHILIC LEUKEMIA-CELLS

In rat basophilic leukemia cells (RBL-2H3) activation of the high affi nity receptor for IgE induces tyrosine phosphorylation of PKC delta. W e carried out solid phase synthesis of 15 amino acid long oligopeptide s corresponding to the sequences around each of the 19 tyrosine residu es in PKC delta. Only three oligopeptides, corresponding to tyrosine 5 2, 155, and 565, were phosphorylated when exposed to lyn kinase. Singl e mutants in each of these three tyrosine residues of PKC delta were p repared. Upon expression in the RBL-2H3 cells, only the mutant in tyro sine 52 showed abolition of the IgE-antigen induced tyrosine phosphory lation.