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  • Title: Inhibition of Na+-Ca2+ exchange in heart sarcolemmal vesicles by phosphatidylethanolamine N-methylation.
    Author: Panagia V, Makino N, Ganguly PK, Dhalla NS.
    Journal: Eur J Biochem; 1987 Aug 03; 166(3):597-603. PubMed ID: 3609028.
    Abstract:
    The effect of phosphatidylethanolamine N-methylation on Na+-Ca2+ exchange was studied in sarcolemmal vesicles isolated from rat heart. Phosphatidylethanolamine N-methylation following incubation of membranes with S-adenosyl-L-methionine, a methyl donor for the enzymatic N-methylation, inhibited Nai+-dependent Ca2+ uptake by about 50%. The N-methylation reaction did not alter the passive permeability of the sarcolemmal vesicles to Na+ and Ca2+ and did not modify the electrogenic characteristics of the exchanger. The depressant effect of phosphatidylethanolamine N-methylation on Nai+-dependent Ca2+ uptake was prevented by S-adenosyl-L-homocysteine, an inhibitor of the N-methylation. Pretreatment of sarcolemma with methyl acetimidate hydrochloride, an amino-group-blocking agent, also prevented methylation-induced inhibition of Ca2+ uptake. In the presence of exogenous phospholipid substrate, the phospholipid N-methylation process in methyl-acetimidate-treated sarcolemmal vesicles was restored and the inhibitory effect on Ca2+ uptake was evident. These results suggest that phosphatidylethanolamine N-methylation influences the heart sarcolemmal Na+-Ca2+ exchange system.
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