A novel serine kinase activated by rac1/CDC42Hs-dependent autophosphorylation is related to PAK65 and STE20

摘要: We identified three proteins in neutrophil cytosol of molecular size 65, 62 and 68 kDa which interact a GTP-dependent manner with rac1 CDC42Hs, but not rho. Purification p65 subsequent peptide sequencing revealed identity to rat brain PAK65 yeast STE20 kinase domains. Based on these sequences we screened human placenta library cloned the full-length cDNA. The complete amino acid sequence cDNA shares approximately PAK65; within domain protein > 95% 63% respectively. new (h)PAK65 mRNA is ubiquitously expressed hPAK65 distinct from either or PAK65. Recombinant exhibits identical specificity endogenous p65; both can bind CDC42Hs manner. GTP-bound forms induce autophosphorylation serine residues only. activated by phosphorylated same sites. Induction stimulates activity towards myelin basic once activated, are no longer required keep it active. affinities rac/CDC42Hs for non-phosphorylated were similar. had only marginal effect intrinsic GTPase significantly affected binding GAP p190. These data consistent model functions as an effector molecule CDC42Hs.