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Activation of SRC family kinases in human neutrophils. Evidence that p58 c‐frg and p53/56 lyn redistributed to a Triton X‐100‐insoluble cytoskeletal fraction, also enriched in the caveolar protein Caveolin , display an enhanced kinase activity
Author(s) -
Fumagalli Laura,
Berton Giorgio
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00029-4
Subject(s) - lyn , cytoskeleton , phosphorylation , tyrosine phosphorylation , tyrosine , tyrosine kinase , microbiology and biotechnology , proto oncogene tyrosine protein kinase src , caveolae , kinase , protein tyrosine phosphatase , tyrosine protein kinase csk , biology , protein tyrosine kinases , receptor tyrosine kinase , chemistry , biochemistry , signal transduction , sh2 domain , cell
Protein tyrosine phosphorylation is one of the signals involved in stimulation of neutrophil (PMN) functions. We found that phorbol myristate acetate (PMA) activates the src family tyrosine kinases p58 c−fgr and p53/56 lyn in suspended PMNs. Moreover, we found that up to about 20% of p58 c−fgr and p53/56 lyn redistribute to a Triton X‐100‐insoluble fraction after PMA stimulation, and it is this fraction of the two kinases which displays an increased activity. These changes of p58 c−fgr and p53/56 lyn distribution and activity correlated with tyrosine phosphorylation of endogenous substrates. In fact, in PMA‐stimulated PMNs tyrosine phosphorylated proteins are mostly recovered in a Triton‐insoluble cell fraction. To separate cytoskeletal from caveolar structures, which both display Triton X‐100‐insolubility, we used the detergent n ‐octyl ß‐ d ‐glucopyranoside (OGP) which solubilises components of caveolae. We found that the caveolae marker protein, caveolin, as well as the cytoskeletal protein α‐actinin and p58 c−fgr and p53/56 lyn , is insoluble in OGP. These findings suggest that PMA stimulation promotes the formation of multimolecular complexes containing cytoskeletal proteins, caveolin‐containing structures and src family protein tyrosine kinases. Moreover, they show that p58 c−fgr and p53/56 lyn associated with this multimolecular complex display an enhanced kinase activity.