Phosphorylation of 338SSYY341 regulates specific interaction between Raf-1 and MEK1

Xiaoqin Xiang, Mengwei Zang, Christine A. Waelde, Rong Wen, Zhijun Luo

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The present study characterizes the interaction between the Raf-1 kinase domain and MEK1 and examines whether the magnitude of their interaction correlates to the ability of Raf to phosphorylate MEK1. Here we show that the minimal domain required for the Raf kinase activity starts from tryptophan 342. Maximal binding of the Raf kinase domain to MEK1 and its kinase activity are achieved upon phosphorylation of the region 338SSYY341 in response to 4β-12-O-tetradecanoylphorbol-13-acetate (TPA), or mutation of Y340Y341 to aspartic acids. Conversely, the TPA-stimulated MEK binding and kinase activity are diminished when this region is deleted or Ser338 and Ser339 are mutated to alanines. We also show that the integrity of the Raf ATP-binding site is necessary for the interaction between Raf-1 and MEK1. Furthermore, two MEK-binding sites are identified; the first is localized between amino acids 325 and 349, and the second is within the region between amino acids 350 and 648. Separately, the binding of each site to MEK1 is weak, but in a cis context, they give rise to a much stronger association, which can be further stimulated by TPA. Finally, we find that tryptophan 342, which is conserved among the Raf family and other protein kinases, is essential for the Ser338 phosphorylation of the full-length Raf and its binding to MEK1. Taken together, our results indicate that the phosphorylation of Ser338 and Tyr341 on Raf exerts an important effect on reconfiguring the two MEK-binding sites. As a result, these two sites coordinate to form a high affinity MEK-binding epitope, leading to a marked increase in Raf kinase activity.

Original languageEnglish
Pages (from-to)44996-45003
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number47
DOIs
StatePublished - Nov 22 2002
Externally publishedYes

Fingerprint

Phosphorylation
raf Kinases
Mitogen-Activated Protein Kinase Kinases
Tetradecanoylphorbol Acetate
Binding Sites
Acetates
Tryptophan
Phosphotransferases
Proto-Oncogene Proteins c-raf
MAP Kinase Kinase Kinases
Amino Acids
Aspartic Acid
Alanine
Protein Kinases
Epitopes
Adenosine Triphosphate
Association reactions
Mutation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Phosphorylation of 338SSYY341 regulates specific interaction between Raf-1 and MEK1. / Xiang, Xiaoqin; Zang, Mengwei; Waelde, Christine A.; Wen, Rong; Luo, Zhijun.

In: Journal of Biological Chemistry, Vol. 277, No. 47, 22.11.2002, p. 44996-45003.

Research output: Contribution to journalArticle

Xiang, Xiaoqin ; Zang, Mengwei ; Waelde, Christine A. ; Wen, Rong ; Luo, Zhijun. / Phosphorylation of 338SSYY341 regulates specific interaction between Raf-1 and MEK1. In: Journal of Biological Chemistry. 2002 ; Vol. 277, No. 47. pp. 44996-45003.
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