Catalytic domain of Fungal Nuclear Dbf2-Related kinase-like Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This group is composed of fungal NDR-like proteins including Saccharomyces cerevisiae CBK1 (or CBK1p), Schizosaccharomyces pombe Orb6 (or Orb6p), Ustilago maydis Ukc1 (or Ukc1p), and Neurospora crassa Cot1. Like NDR kinase, group members contain an N-terminal regulatory (NTR) domain and an insert within the catalytic domain that contains an auto-inhibitory sequence. CBK1 is an essential component in the RAM (regulation of Ace2p activity and cellular morphogenesis) network. CBK1 and Orb6 play similar roles in coordinating cell morphology with cell cycle progression. Ukc1 is involved in morphogenesis, pathogenicity, and pigment formation. Cot1 plays a role in polar tip extension.The fungal NDR subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.