Catalytic domain of Microtubule-associated serine/threonine (MAST) kinase-like proteins
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This subfamily includes MAST kinases, MAST-like (MASTL) kinases (also called greatwall kinase or Gwl), and fungal kinases with similarity to Saccharomyces cerevisiae Rim15 and Schizosaccharomyces pombe cek1. MAST kinases contain an N-terminal domain of unknown function, a central catalytic domain, and a C-terminal PDZ domain that mediates protein-protein interactions. MASTL kinases carry only a catalytic domain which contains a long insert relative to other kinases. The fungal kinases in this subfamily harbor other domains in addition to a central catalytic domain, which like in MASTL, also contains an insert relative to MAST kinases. Rim15 contains a C-terminal signal receiver (REC) domain while cek1 contains an N-terminal PAS domain. MAST kinases are cytoskeletal associated kinases of unknown function that are also expressed at neuromuscular junctions and postsynaptic densities. MASTL/Gwl is involved in the regulation of mitotic entry, mRNA stabilization, and DNA checkpoint recovery. The fungal proteins Rim15 and cek1 are involved in the regulation of meiosis and mitosis, respectively. The MAST-like kinase 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.