Stimulation of Phosphorylation of Tyr394 by Hydrogen Peroxide Reactivates Biologically Inactive, Non-membrane-bound Forms of Lck

Phe mutant of Lck (F505Lck) exhibits elevated biological activity and constitutive phosphorylation of Tyr-394 in vivo. Mutations at sites of fatty acylation that prevent F505Lck from associating with cellular membranes abolish the biological activity as a protein kinase in vivo and in vitro, and eliminate the phosphorylation of Tyr-394. Here, we show that exposure of cells expressing cytoplasmic or nuclear forms of F505Lck to H2O2, a general inhibitor of tyrosine protein phosphatases, restores the catalytic activity of these mutant proteins through stimulation of phosphorylation of Tyr-394. H2O2 treatment induced the phosphorylation of Tyr-394 therefore need not occur by autophosphorylation. Thus, there appear to be two mechanisms through which the phosphorylation of Lck at Tyr-394 can occur. One is restricted to the plasma membrane and does not require the presence of oxidants. The other is operational in the nucleus as well as the cytosol and is responsive to oxidants. -->

ISSN:	0021-9258
DOI:	10.1074/jbc.271.21.12549
Přístupová URL adresa:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2d190b0b021118c05577de5d8c584ddd https://doi.org/10.1074/jbc.271.21.12549
Rights:	OPEN
Přírůstkové číslo:	edsair.doi.dedup.....2d190b0b021118c05577de5d8c584ddd
Autor:	James S. Hardwick, Lara K. Yurchak, Kathryn Pierno, Bartholomew M. Sefton, Kurt E. Amrein
Rok vydání:	1996
Předmět:	inorganic chemicals Molecular Sequence Data Protein tyrosine phosphatase Biology Biochemistry Catalysis Cell Line Substrate Specificity Phosphorylation cascade Enzyme Reactivators Palmitoylation Animals Protein phosphorylation Amino Acid Sequence Phosphorylation Protein kinase A Molecular Biology Base Sequence Cell Membrane Autophosphorylation Hydrogen Peroxide Cell Biology Rats src-Family Kinases Lymphocyte Specific Protein Tyrosine Kinase p56(lck) Tyrosine Fatty acylation
Zdroj:	Journal of Biological Chemistry. 271:12549-12554
ISSN:	0021-9258
DOI:	10.1074/jbc.271.21.12549
Popis:	Lck, a lymphocyte-specific tyrosine protein kinase, is bound to cellular membranes as the result of myristoylation and palmitoylation of its amino terminus. Its activity is inhibited by phosphorylation of tyrosine 394. The Tyr-505 --> Phe mutant of Lck (F505Lck) exhibits elevated biological activity and constitutive phosphorylation of Tyr-394 in vivo. Mutations at sites of fatty acylation that prevent F505Lck from associating with cellular membranes abolish the biological activity as a protein kinase in vivo and in vitro, and eliminate the phosphorylation of Tyr-394. Here, we show that exposure of cells expressing cytoplasmic or nuclear forms of F505Lck to H2O2, a general inhibitor of tyrosine protein phosphatases, restores the catalytic activity of these mutant proteins through stimulation of phosphorylation of Tyr-394. H2O2 treatment induced the phosphorylation of Tyr-394 therefore need not occur by autophosphorylation. Thus, there appear to be two mechanisms through which the phosphorylation of Lck at Tyr-394 can occur. One is restricted to the plasma membrane and does not require the presence of oxidants. The other is operational in the nucleus as well as the cytosol and is responsive to oxidants.
Databáze:	OpenAIRE
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