Phospholipid metabolism in the molluscs. II. Activities of choline kinase, ethanolamine kinase, and CTP:phosphorylethanolamine cytidyltransferase in the mollusc Helix lactea

Abstract
The distribution of phospholipids in the mollusc Helix lactea was investigated. The results showed that ethanolamine and choline phosphoglycerides are the major phospholipids in this species, amounting to 49% and 26% of the total lipid phosphorus. The amount of ceramide 2-aminoethylphosphonate was 9% of the total phospholipids and this compound was the only phosphonolipid detected in this species. Ethanolamine and choline kinase activities were shown to be present in the high-speed supernatant fraction of snail digestive gland. The maximum activity of choline kinase was found to be higher than that of ethanolamine kinase in the same enzyme preparation. The enzyme CTP:phosphorylethanolamine cytidyltransferase was also demonstrated in the high-speed supernatant fraction of snail digestive gland. The enzymic reaction product was identified as CDP-ethanolamine by paper chromatography and radioautography. The enzymes phosphorylcholine cytidyltransferase and aminoethylphosphonate cytidyltransferase were not detected under the conditions employed in the phosphorylethanolamine cytidyltransferase assays.