Catalytic domain of RCK1-like Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This subfamily is composed of fungal STKs including Saccharomyces cerevisiae RCK1 and RCK2, Schizosaccharomyces pombe Sty1-regulated kinase 1 (Srk1), and similar proteins. RCK1, RCK2 (or Rck2p), and Srk1 are MAPK-activated protein kinases. RCK1 and RCK2 are involved in oxidative and metal stress resistance in budding yeast. RCK2 also regulates rapamycin sensitivity in both S. cerevisiae and Candida albicans. Srk1 is activated by Sty1/Spc1 and is involved in negatively regulating cell cycle progression by inhibiting Cdc25. The RCK1-like 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.