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PAK Signaling in Fission Yeast

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Simple eukaryotes such as yeasts and molds encode multiple PAKs (p21-Activated Kinases) that, like their orthologs in other systems, act downstream of Rho-family GTPases. All PAKs contain an N-terminal PBD (p21 GTPase-Binding-Domain), which confers binding to small GTPases such as CDC42 (Cell Division Cycle-42) or Rac, and a C-terminal protein kinase domain, but they do not bind to Rho, Ras, or other small G-proteins. CDC42 and Rac bind in a GTP-dependent fashion to a highly conserved sequence, referred to as the CRIB (CDC42 and Rac Interactive Binding) domain, found in the N-terminal regulatory domains of all characterized PAKs (Ref.1).

The fission yeast Schizosaccharomyces pombe encodes two PAK kinases–Pak1/Shk1 and Pak2/Shk2–both of which, like their counterparts in budding yeast regulate of MAPK [...]


1.Shk1, a homolog of the Saccharomyces cerevisiae Ste20 and mammalian p65PAK protein kinases, is a component of a Ras/Cdc42 signaling module in the fission yeast Schizosaccharomyces pombe.
Marcus S, Polverino A, Chang E, Robbins D, Cobb MH, Wigler MH.
Proc Natl Acad Sci U S A. 1995 Jun 20; 92(13):6180-4.
2.The highly conserved SKB1 gene encodes a protein that interacts with Shk1, a fission yeast Ste20/PAK homolog.
Gilbreth M, Yang P, Wang D, Frost J, Polverino A, Cobb MH, Marcus S.
Proc Natl Acad Sci U S A. 1996 Nov 26; 93(24):13802-7.
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