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.
Autero
Matti
M
Department of Biosciences, Division of Biochemistry, University of Helsinki, Helsinki, Finland.
Heiska
Leena
L
Rönnstrand
Lars
L
Vaheri
Antti
A
Gahmberg
Carl G
CG
Carpén
Olli
O
D002460:Cell Line; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D019169:Jurkat Cells; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014162:Transfection; D000099149:Ezrin
D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D017493:Leukocyte Common Antigens; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D000099149:Ezrin