ABSTRACT
The cholinephosphotranseferase (CPT) reaction is the dominant means for generating phosphatidylcholine in cells of animal or plant origin. The differences in activities among membrane fractions might reflect in part the variation in diglyceride (DG) content rather than CPT content. CPT activity has also been described in neuronal nuclear membranes and in lung mitochon-drial preparations. CPT activity is diminished or destroyed by treatment of isolated intact microsomes of liver or brain with a variety of proteases or with mercury-dextran. CPT activity is typically measured by monitoring transfer of methyl-labeled phosphocholine from Cytidylyltransferase (CDP)-choline to a DG acceptor. CPT activity has also been measured by monitoring the transfer of label from DG in the presence of cold CDP-choline. Pontoni et al. also studied the catalytic mechanism of rat liver microsomal CPT by kinetic analysis. Rosemary Cornell and D. H. MacLennan compared the detergent concentration curves for inactivation and solubilization of sarcoplasmic reticulum membranes containing CPT.
