Document Detail

Serine/threonine kinase activation in human neutrophils: relationship to tyrosine phosphorylation.
MedLine Citation:
PMID:  7810598     Owner:  NLM     Status:  MEDLINE    
Tyrosine phosphorylation is among the earliest responses of neutrophils to chemotactic peptides. Tyrosine phosphorylated proteins comigrate with serine/threonine kinases of 65 and 72 kDa (PK65 and PK72), which are activated concomitantly by the chemoattractants. Studies were designed to test whether tyrosine phosphorylation is required for activation of PK65 and PK72. Pretreatment of cells with the tyrosine kinase inhibitors erbstatin or genistein prevented both phosphotyrosine accumulation and activation of PK65 and PK72. In nondenaturing lysates, PK65 and PK72 became spontaneously inactivated in parallel with rapid endogenous tyrosine dephosphorylation. Spontaneous dephosphorylation and inactivation of PK65 and PK72 were prevented in denatured lysates. Under these conditions, dephosphorylation could be induced by exogenous phosphotyrosine phosphatase 1B. PK65 and PK72 activation persisted despite virtually complete tyrosine dephosphorylation. Moreover, immunoprecipitation experiments indicated that PK65 and PK72 are not themselves tyrosine phosphorylated. We concluded that tyrosine phosphorylation is a necessary upstream event in the activation of the serine/threonine kinases. However, once the posttranslational modification that renders PK65 and PK72 active has occurred, tyrosine phosphorylation is no longer required for maintenance of their kinase activity.
J H Brumell; S Grinstein
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  267     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1994 Dec 
Date Detail:
Created Date:  1995-01-31     Completed Date:  1995-01-31     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  C1574-81     Citation Subset:  IM    
Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.
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MeSH Terms
Enzyme Activation
Molecular Weight
Neutrophils / enzymology*
Oxazoles / pharmacology
Phosphoprotein Phosphatases / antagonists & inhibitors
Protein-Serine-Threonine Kinases / physiology*
Protein-Tyrosine Kinases / antagonists & inhibitors
Tyrosine / metabolism*
Reg. No./Substance:
0/Oxazoles; 101932-71-2/calyculin A; 55520-40-6/Tyrosine; EC Kinases; EC Kinases; EC Phosphatases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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