ABSTRACT

The reaction catalyzed by CTP:cholinephosphate cytidylyltransferase (CT) was first described by E. P. Kennedy and S. B. Weiss in 1956. The bulk of the activity of CT in pea stems was recovered from the cytosol, and this activity was not stimulated by phospholipids. The CT from yeast also appeared to be mostly a hydrophilic protein, even though it is found mainly in the membrane fraction of the cells. Cytosolic CT appears to be a reservoir of enzyme that can be mobilized at short notice. A stimulation of phosphatidylcholine (PC) synthesis by fatty acids was observed which was attributed to activation of CT by binding to membranes. The studies in the fetal/newborn lung are the only indications that fatty acid regulation of CT and PC biosynthesis is an important physiological phenomenon. The cDNA probe will allow for the identification of the chromosome that contains the gene for CT and permit the cloning and sequencing of the CT gene.