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Identification of the regulatory phosphorylation sites in pp42/mitogen‐activated protein kinase (MAP kinase).
Author(s) -
Payne D. M.,
Rossomando A. J.,
Martino P.,
Erickson A. K.,
Her J. H.,
Shabanowitz J.,
Hunt D. F.,
Weber M. J.,
Sturgill T. W.
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.tb08021.x
Subject(s) - phosphopeptide , map2k7 , mapk14 , biology , biochemistry , cyclin dependent kinase 2 , map kinase kinase kinase , mitogen activated protein kinase kinase , phosphorylation , protein phosphorylation , c raf , protein kinase a , kinase , mitogen activated protein kinase , protein serine threonine kinases , microbiology and biotechnology
Mitogen‐activated protein kinase (MAP kinase) is a 42 kd serine/threonine protein kinase whose enzymatic activity requires phosphorylation of both tyrosyl and threonyl residues. As a step in elucidating the mechanism(s) for activation of this enzyme, we have determined the sites of regulatory phosphorylation. Following proteolytic digestion of 32P‐labeled pp42/MAP kinase with trypsin, only a single phosphopeptide was detected by two‐dimensional peptide mapping, and this peptide contained both phosphotyrosine and phosphothreonine. The amino acid sequence of the peptide, including the phosphorylation sites, was determined using a combination of Fourier transform mass spectrometry and collision‐activated dissociation tandem mass spectrometry with electrospray ionization. The sequence for the pp42/MAP kinase tryptic phosphopeptide is similar (but not identical) to a sequence present in the ERK1‐ and KSS1‐encoded kinases. The two phosphorylation sites are separated by only a single residue. The regulation of activity by dual phosphorylations at closely spaced threonyl and tyrosyl residues has a functional correlate in p34cdc2, and may be characteristic of a family of protein kinases regulating cell cycle transitions.