Catalytic domain of fungal Rim15-like Protein Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. Members of this group include Saccharomyces cerevisiae Rim15, Schizosaccharomyces pombe cek1, and similar fungal proteins. They contain a central catalytic domain, which contains an insert relative to MAST kinases. In addition, Rim15 contains a C-terminal signal receiver (REC) domain while cek1 contains an N-terminal PAS domain. Rim15 (or Rim15p) functions as a regulator of meiosis. It acts as a downstream effector of PKA and regulates entry into stationary phase (G0). Thus, it plays a crucial role in regulating yeast proliferation, differentiation, and aging. Cek1 may facilitate progression of mitotic anaphase. The Rim15-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.