Functional expression of a MAP kinase kinase in COS cells and recognition by an anti-STE7/byr1 antibody.

Journal Article

Mitogen-activated protein (MAP) kinases p42mapk and p44mapk are activated by dual tyrosine and threonine phosphorylation in vivo. Both MAPKs are phosphorylated and activated in vitro by an activator recently identified as a protein-tyrosine/threonine kinase. We have isolated a putative cDNA for a MAP kinase kinase (MAPKK) and determined its structure [Proc. Natl. Acad. Sci. USA, in press]. The protein encoded by this cDNA shares sequence homology with two yeast protein kinases byr1 and STE7. We now report that stimulation with serum of COS cells expressing this shares sequence homology with two yeast protein kinases byr1 and STE7. We now report that stimulation with serum of COS cells expressing this protein amplifies MAPK activator activity markedly. The increased activity co-migrates during chromatography with the expressed 45 kDa protein, recognized by an anti-STE7/byr1 antibody, and is abrogated by treatment with phosphatase 2A. Thus, this cDNA encodes a functional MAPKK. The anti-STE7/byr1 antibody also recognized a 46 kDa COS cell protein that was resolved from the expressed MAPKK by anion-exchange chromatography. This immunoreactive protein co-eluted with endogenous MAPKK activity, suggesting identification of the immunoreactive band as monkey MAPKK.

Full Text

Duke Authors

Cited Authors

  • Haystead, CM; Wu, J; Gregory, P; Sturgill, TW; Haystead, TA

Published Date

  • February 8, 1993

Published In

Volume / Issue

  • 317 / 1-2

Start / End Page

  • 12 - 16

PubMed ID

  • 8428620

International Standard Serial Number (ISSN)

  • 0014-5793

Language

  • eng

Conference Location

  • England