ABSTRACT
An area of considerable interest has been the high inducibility of Choline kinase (CK) under certain experimental conditions and its possible relation to regulation of net phosphatidylcholine biosynthesis. The notion that choline transport is an important aspect of a functioning cholinergic nerve terminal has long been suspected. Choline is a dietary requirement that crosses the cell membrane before being phosphorylated by CK or metabolized in liver or kidney by mitochondrial enzymes, i.e., choline dehydrogenase and betaine aldehyde dehydrogenase to betaine which can donate a methyl group to homocysteine for the formation of methionine. The choline transport system in erythrocytes has been studied despite its unclear physiological function. Evidence for the existence of separate kinases for the phosphorylation of choline and ethanolamine has been reported in some plant tissues, rumen protozoon, C. pipiens fatigans, and in animal liver.
