cd06648: STKc_PAK_II (this model, PSSM-Id:132979 is obsolete and has been replaced by 270815)
Catalytic domain of the Protein Serine/Threonine Kinase, Group II p21-activated kinase
Serine/threonine kinases (STKs), p21-activated kinase (PAK) subfamily, Group II, 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 from higher eukaryotes are classified into two groups (I and II), according to their biochemical and structural features. Group II PAKs, also called non-conventional PAKs, include PAK4, PAK5, and PAK6. Group II PAKs contain PBD (p21-binding domain) and catalytic domains, but lack other motifs found in group I PAKs, such as an AID (autoinhibitory domain) and SH3 binding sites. Since group II PAKs do not contain an obvious AID, they may be regulated differently from group I PAKs. While group I PAKs interact with the SH3 containing proteins Nck, Grb2 and PIX, no such binding has been demonstrated for group II PAKs. Some known substrates of group II PAKs are also substrates of group I PAKs such as Raf, BAD, LIMK and GEFH1. Unique group II substrates include MARK/Par-1 and PDZ-RhoGEF. Group II PAKs play important roles in filopodia formation, neuron extension, cytoskeletal organization, and cell survival.