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Biochem/physiol Actions

MAPKAPK2 is a serine/threonine protein kinase activated by the p38 MAP kinase in response to various signals including mitogenic and stress stimuli. MAPKAPK2 is distinguished from the RSK family of ribosomal protein S6 kinases (also termed MAPKAPK1), which are activated by the MAP kinases, ERK1, and ERK2 based on its substrate specificity and amino acid sequence. Upon activation, p38 MAP kinase activates the downstream MAPKAPK2 by phosphorylation of the threonine residue in the Pro-Thr motif in response to heat shock or mitogenic stimuli. Activated MAPKAPK2 phosphorylates the small heat shock protein HSP25/HSP27, both in vitro and in vivo, at serine residues. Thus, HSP25/HSP27 seems to be the physiological substrate of MAPKAPK2.

Physical form

Solution in 50 mM Tris-HCl, pH 7.4, 100 mM NaCl, 0.05 mM EDTA, 2 mM DTT, and 10% glycerol.

Unit Definition

One unit will incorporate 1.0 nmole of phosphate into HSP 25 per minute at 30 °C at pH 7.4.