cd06647: STKc_PAK_I (this model, PSSM-Id:132978 is obsolete and has been replaced by 270814)
Catalytic domain of the Protein Serine/Threonine Kinase, Group I p21-activated kinase
Serine/threonine kinases (STKs), p21-activated kinase (PAK) subfamily, Group I, catalytic (c) domain. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The PAK subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. PAKs are Rho family GTPase-regulated kinases that serve as important mediators in the function of Cdc42 (cell division cycle 42) and Rac. PAKs are implicated in the regulation of many cellular processes including growth factor receptor-mediated proliferation, cell polarity, cell motility, cell death and survival, and actin cytoskeleton organization. PAKs from higher eukaryotes are classified into two groups (I and II), according to their biochemical and structural features. Group I PAKs, also called conventional PAKs, include PAK1, PAK2, and PAK3. Group I PAKs contain a PBD (p21-binding domain) overlapping with an AID (autoinhibitory domain), a C-terminal catalytic domain, SH3 binding sites and a non-classical SH3 binding site for PIX (PAK-interacting exchange factor). They interact with the SH3 domain containing proteins Nck, Grb2 and PIX. Binding of group I PAKs to activated GTPases leads to conformational changes that destabilize the AID, allowing autophosphorylation and full activation of the kinase domain. Known group I PAK substrates include MLCK, Bad, Raf, MEK1, LIMK, Merlin, Vimentin, Myc, Stat5a, and Aurora A, among others.