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C-terminal catalytic domain of the Serine/Threonine Kinase, Ribosomal S6 kinase 3 (also called Ribosomal protein S6 kinase alpha-2 or 90kDa ribosomal protein S6 kinase 2) STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. RSK3 is also called S6K-alpha-2, RPS6KA2, p90RSK2 or MAPK-activated protein kinase 1c (MAPKAPK-1c). RSK3 binds muscle A-kinase anchoring protein (mAKAP)-b directly and regulates concentric cardiac myocyte growth. The RSK3 gene, RPS6KA2, is a putative tumor suppressor gene in sporadic epithelial ovarian cancer and variations to the gene may be associated with rectal cancer risk. RSK3 is one of four RSK isoforms (RSK1-4) from distinct genes present in vertebrates. 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. The RSK3 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.",