cd05582: STKc_RSK_N (this model, PSSM-Id:173673 is obsolete and has been replaced by 270734)
N-terminal catalytic domain of the Protein Serine/Threonine Kinase, 90 kDa ribosomal protein S6 kinase
Serine/Threonine Kinases (STKs), 90 kDa ribosomal protein S6 kinase (RSK) subfamily, N-terminal catalytic (c) domain. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The RSK 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. RSKs contain an N-terminal kinase domain (NTD) from the AGC family and a C-terminal kinase domain (CTD) from the CAMK family. They are activated by signaling inputs from extracellular regulated kinase (ERK) and phosphoinositide dependent kinase 1 (PDK1). ERK phosphorylates and activates the CTD of RSK, serving as a docking site for PDK1, which phosphorylates and activates the NTD, which in turn phosphorylates all known RSK substrates. RSKs act as downstream effectors of mitogen-activated protein kinase (MAPK) and play key roles in mitogen-activated cell growth, differentiation, and survival. Mammals possess four RSK isoforms (RSK1-4) from distinct genes. RSK proteins are also referred to as MAP kinase-activated protein kinases (MAPKAPKs), p90-RSKs, or p90S6Ks.