Catalytic domain of the Serine/Threonine Kinases, Oxidative stress response kinase and Ste20-related proline alanine-rich kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. SPAK is also referred to as STK39 or PASK (proline-alanine-rich STE20-related kinase). OSR1 and SPAK regulate the activity of cation-chloride cotransporters through direct interaction and phosphorylation. They are also implicated in cytoskeletal rearrangement, cell differentiation, transformation and proliferation. OSR1 and SPAK contain a conserved C-terminal (CCT) domain, which recognizes a unique motif ([RK]FX[VI]) present in their activating kinases (WNK1/WNK4) and their substrates. The OSR1 and SPAK 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",