Phosphorylation site specificity of the Pak‐mediated regulation of Raf‐1 and cooperativity with Src

FEBS Letters

Wireman, Randall S.¹  Marshall, Mark S.¹  King, Alastair J.¹  Hamilton, Mark² 

[1] Division of Hematology/Oncology, Department of Medicine, Indiana University School of Medicine, 1044 West Walnut Street, Indianapolis, IN 46202, USA;Lilly Research Laboratories, One Corporate Plaza, Drop Code 1543, Indianapolis, IN 46285, USA

关键词: Raf-1;    Ras;    p21-activated protein kinase;    Src;    Protein kinase;    Specificity;    Cooperativity;    Phosphorylation;    Pak;    p21-activated protein kinase;    CR3;    conserved region 3 of Raf-1;    TGF;    transforming growth factor;   

DOI  :  10.1016/S0014-5793(01)02425-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The p21-activated kinase, Pak, has recently been shown to phosphorylate Raf-1 on serine 338 (S338), a critical regulatory residue. The specificity requirements for Pak-mediated phosphorylation of S338 were examined by substitution analysis of Raf-1 peptides and conserved region 3 (CR3) proteins. Phosphorylation was found to be very sensitive to alterations in amino acid side chains proximal to S338. Loss of N-terminal arginines resulted in decreased peptide phosphorylation while loss of these residues, as well as C-terminal glutamates and bulky C-terminal hydrophobic residues, decreased phosphorylation of the CR3 protein. Phosphorylation of Raf-1 on tyrosine 341 is significant in epidermal growth factor- and Src-mediated signaling, suggesting that cooperativity may exist between Pak and Src phosphorylation of Raf-1. Purified Pak and Src were found not to be cooperative in phosphorylating peptides or purified CR3 protein. However, the phosphorylation of Raf-1 S338 by Pak was increased in the presence of Src. The complexity of this signaling module could thus account for the different levels of Raf-1 activation required for fulfillment of different biological roles within the cell.

【 授权许可】

Unknown