Phospholipid-synthesizing Enzymes Associated with Golgi Dictyosomes from Pea Tissue

Abstract

Golgi dictyosomal membranes isolated from pea (Pisum sativum) stem tissue, using a combination of rate zonal and isopycnic sucrose density centrifugation, were shown to bear cytidine diphosphate-choline:diglyceride phosphorylcholinetransferase, CDP-ethanolamine:diglyceride phosphorylethanolaminetransferase, and CTP:phosphorylcholine cytidyltransferase activities. Although the majority of the activity of the phospholipid-synthesizing enzymes was associated with the endoplasmic reticulum, the activity found in the Golgi system was about 25% of the total activity. These results suggest that Golgi dictyosomes probably synthesize at least part of the membrane phospholipids that they may need for their secretory function and for dictyosomal proliferation during cell growth, rather than importing this material entirely from the endoplasmic reticulum.