Catalytic domain of the Serine/Threonine Kinase, p21-activated kinase 2
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PAK2 plays a role in pro-apoptotic signaling. It is cleaved and activated by caspases leading to morphological changes during apoptosis. PAK2 is also activated in response to a variety of stresses including DNA damage, hyperosmolarity, serum starvation, and contact inhibition, and may play a role in coordinating the stress response. PAK2 also contributes to cancer cell invasion through a mechanism distinct from that of PAK1. It belongs to the group I PAKs, which 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). PAKs are Rho family GTPase-regulated kinases that serve as important mediators in the function of Cdc42 (cell division cycle 42) and Rac. 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.