Catalytic domain of Fungal Sid2p-like Protein Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This group contains fungal kinases including Schizosaccharomyces pombe Sid2p and Saccharomyces cerevisiae Dbf2p. Group members show similarity to NDR kinases in that they contain an N-terminal regulatory (NTR) domain and an insert within the catalytic domain that contains an auto-inhibitory sequence. Sid2p plays a crucial role in the septum initiation network (SIN) and in the initiation of cytokinesis. Dbf2p is important in regulating the mitotic exit network (MEN) and in cytokinesis. The Sid2p-like group 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.