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Catalytic domain of the Serine/Threonine Kinase, Kinase Suppressor of Ras 1 STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. KSR1 functions as a transducer of TNFalpha-stimulated C-Raf activation of ERK1/2 and NF-kB. Detected activity of KSR1 is cell type specific and context dependent. It is inactive in normal colon epithelial cells and becomes activated at the onset of inflammatory bowel disease (IBD). Similarly, KSR1 activity is undetectable prior to stimulation by EGF or ceramide in COS-7 or YAMC cells, respectively. KSR proteins are widely regarded as pseudokinases, however, this matter is up for debate as catalytic activity has been detected for KSR1 in some systems. The KSR1 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.",