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Euykaryotic Ethanolamine kinase ETNK catalyzes the transfer of the gamma-phosphoryl group from CTP to ethanolamine (Etn), the first step in the CDP-Etn pathway for the formation of the major phospholipid, phosphatidylethanolamine (PtdEtn). Unlike ChoK, ETNK shows specific activity for its substrate, and displays negligible activity towards N-methylated derivatives of Etn. The Drosophila ETNK is implicated in development and neuronal function. Mammals contain two ETNK proteins, ETNK1 and ETNK2. ETNK1 selectively increases Etn uptake and phosphorylation, as well as PtdEtn synthesis. ETNK2 is found primarily in the liver and reproductive tissues. It plays a critical role in regulating placental hemostasis to support late embryonic development. It may also have a role in testicular maturation. ETNK is part of a larger superfamily that includes the catalytic domains of other kinases, such as the typical serine/threonine/tyrosine protein kinases (PKs), RIO kinases, actin-fragmin kinase (AFK), and phosphoinositide 3-kinase (PI3K). |
Jiyao W et al.(2023). "The conserved domain database in 2023.",