Catalytic domain of the Serine/Threonine kinase, Mitogen-activated protein kinase-activated protein kinase 5
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. MAPK-activated protein kinase 5 (MAPKAP5 or MK5) is also called PRAK (p38-regulated/activated protein kinase). It contains a catalytic kinase domain followed by a C-terminal autoinhibitory region that contains nuclear localization (NLS) and nuclear export (NES) signals with a p38 MAPK docking motif that overlaps the NLS. MK5 is a ubiquitous protein that is implicated in neuronal morphogenesis, cell migration, and tumor angiogenesis. It interacts with PKA, which induces cytoplasmic translocation of MK5. Its substrates includes p53, ERK3/4, Hsp27, and cytosolic phospholipase A2 (cPLA2). The MAPKAPK 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.