Ezrin is a substrate for Lck in T cells.

• We evaluated the role of Lck tyrosine kinase, an early effector of T cell activation, in regulation of the membrane-cytoskeleton linker protein ezrin. Ezrin was constitutively tyrosine phosphorylated in wild-type and CD45-deficient Jurkat T cells, but not in Lck-deficient cells. However, phosphorylation was evident in cells, in which Lck activity had been restored by transfection. Phosphorylation was reduced by the Src family kinase inhibitor PP2 and increased by the tyrosine phosphatase inhibitor pervanadate, implying continuous tyrosine phosphorylation and dephosphorylation. Lck phosphorylated ezrin in vitro, and the major phosphotyrosine was identified as Y145. These results identify ezrin as the first cytoskeletal substrate for Lck.

Nyckelord

Antigens; CD45/biosynthesis

Cell Line

Cytoskeletal Proteins

Enzyme Inhibitors/pharmacology

Humans

Immunoblotting

Jurkat Cells

Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/antagonists & inhibitors/deficiency/genetics/*metabolism

Peptide Mapping

Phosphoproteins/chemistry/genetics/*metabolism

Phosphorylation/drug effects

Recombinant Fusion Proteins/genetics/metabolism

T-Lymphocytes/drug effects/*metabolism

Transfection

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