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Catalytic domain of the Serine/Threonine Kinase, p21-activated kinase STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. 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. PAK deregulation is associated with tumor development. PAKs from higher eukaryotes are classified into two groups (I and II), according to their biochemical and structural features. 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). Group II PAKs contain a PBD and a catalytic domain, but lack other motifs found in group I PAKs. Since group II PAKs do not contain an obvious AID, they may be regulated differently from group I PAKs. Group I PAKs interact with the SH3 containing proteins Nck, Grb2 and PIX; no such binding has been demonstrated for group II PAKs. The PAK subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",