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A mammalian protein kinase with potential for serine/threonine and tyrosine phosphorylation is related to cell cycle regulators.
Author(s) -
BenDavid Y.,
Letwin K.,
Tannock L.,
Bernstein A.,
Pawson T.
Publication year - 1991
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1991.tb07952.x
Subject(s) - biology , map2k7 , cyclin dependent kinase 1 , biochemistry , c raf , protein phosphorylation , cyclin dependent kinase 2 , akt3 , protein tyrosine phosphatase , sh3 domain , receptor tyrosine kinase , sh2 domain , tyrosine phosphorylation , protein kinase a , tyrosine , phosphorylation , serine , threonine , cell cycle , gene
In a screen of mouse erythroleukemia cDNA expression libraries with anti‐phosphotyrosine antibodies, designed to isolate tyrosine kinase coding sequences, we identified several cDNAs encoding proteins identical or very similar to known protein‐tyrosine kinases. However, two frequently isolated cDNAs, clk and nek, encode proteins which are most closely related to protein kinases involved in regulating progression through the cell cycle, and contain motifs generally considered diagnostic of protein‐serine/threonine kinases. The clk gene product contains a C‐terminal cdc2‐like kinase domain, most similar to the FUS3 catalytic domain. The Clk protein, expressed in bacteria, becomes efficiently phosphorylated in vitro on tyrosine as well as serine/threonine, and phosphorylates the exogenous substrate poly(glu, tyr) on tyrosine. Direct biochemical evidence indicates that both protein‐tyrosine and protein‐serine/threonine kinase activities are intrinsic to the Clk catalytic domain. These results suggest the existence of a novel class of protein kinases, with an unusual substrate specificity, which may be involved in cell cycle control.