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FUNCTION Catalyzes the three sequential steps of the methylation pathway for the biosynthesis of phosphatidylcholine, a critical and essential component for membrane structure (PubMed:12431977, PubMed:15927961). Uses S-adenosylmethionine (S-adenosyl-L-methionine, SAM or AdoMet) as the methyl group donor for the methylation of phosphatidylethanolamine (1,2-diacyl-sn-glycero-3-phosphoethanolamine, PE) to phosphatidylmonomethylethanolamine (1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine, PMME), PMME to phosphatidyldimethylethanolamine (1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine, PDME), and PDME to phosphatidylcholine (1,2-diacyl-sn-glycero-3-phosphocholine, PC), producing S-adenosyl-L-homocysteine in each step (PubMed:12431977, PubMed:15927961). Responsible for approximately 30% of hepatic PC with the CDP-choline pathway accounting for the other 70% (Probable).FUNCTION Catalyzes the three sequential steps of the methylation of 1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine (PMME) to 1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine (PDME) more efficiently than isoform 2 (PubMed:20860552). Induces increase in PC species with longer polyunsaturated chains than isoform 2 (PubMed:20860552).FUNCTION Produces a higher increase in the level of PC species containing long chains with three double bonds than isoform 1.CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = a 1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = a 1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-methionine = a 1,2-diacyl-sn-glycero-3-phosphocholine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-methionine = a 1,2-diacyl-sn-glycero-3-phosphocholine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phosphoethanolamine + S-adenosyl-L-methionine = a 1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phosphoethanolamine + S-adenosyl-L-methionine = a 1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphoethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z,12Z,15Z-octadecatrienoyl)-sn-glycero-3-phosphoethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z,12Z,15Z-octadecatrienoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z,12Z,15Z-octadecatrienoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z,12Z,15Z-octadecatrienoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1,2-di-(9Z,12Z,15Z-octadecatrienoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-methionine = 1,2-di-(9Z,12Z,15Z-octadecatrienoyl)-sn-glycero-3-phosphocholine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phosphoethanolamine + S-adenosyl-L-methionine = 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phospho-N-methylethanolamine + S-adenosyl-L-methionine = 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-homocysteine + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phospho-N,N-dimethylethanolamine + S-adenosyl-L-methionine = 1-hexadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phosphocholine + S-adenosyl-L-homocysteine + H(+)ACTIVITY REGULATION The first methylation is rate-limiting.PATHWAY Phospholipid metabolism; phosphatidylcholine biosynthesis.INTERACTION localized in the endoplasmic reticulum (ER) of the liver and in a lipid metabolism-rich region of the ER known as mitochondria-associated membranes (PubMed:15927961). Adopts a topography within the ER membrane that positions both termini in the cytosol (PubMed:12431977).SUBCELLULAR LOCATION Found in endoplasmic reticulum where most PEMT activity is generated and in mitochondria.SUBCELLULAR LOCATION Primarily expressed in liver (at protein level).PTM Isoform 2 is N-glycosylated with high-mannose oligosaccharides.SIMILARITY Belongs to the class VI-like SAM-binding methyltransferase superfamily. PEMT/PEM2 methyltransferase family.
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