A family of protein kinases located upstream of the MAP kinases andresponsible for their activation has been identified. The prototype member ofthis family, designated MAP kinase kinase, or MEK-1, specifically phospho-rylates the MAP kinase regulatory threonine and tyrosine residues present inthe Thr-Glu-Tyr motif of ERK. A second MEK family member, MEK-2, resem-bles MEK-1 in its substrate specificity. MEK-3 (or MKK-3) functions to acti-vate p38 MAP kinase, and MEK-4 (also called SEK1 or MKK-4) activatesboth p38 and JNK MAP kinases. MEK-5 appears to specifically phosphory-late ERK5, whereas MEK-6 phosphorylates p38 and p38b. MEK-7 (or MKK-7)phosphorylates and activates the JNK signal transduction pathway.1) Han, J., et al. 1996. J. Biol. Chem. 271: 2886-2891. Jiang, Y., et al. 1996. J. Biol. Chem. 271: 17920-17926. Tournier, C., et al. 1997. Proc. Natl. Acad. Sci. USA94: 7337-7442. Holland, P. M., et al. 1997. J. Biol. Chem. 272: 24994-24998.
Immunogen
MEK5 antibody was raised against a peptide sequence around aa. 311-315 (K-T-Y-V-G ) derived from Rat MEK5.