Catalyzes the three sequential steps of the methylation pathway for the biosynthesis of phosphatidylcholine, a critical and essential component for membrane structure (, ). 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 (, ). Responsible for approximately 30% of hepatic PC with the CDP-choline pathway accounting for the other 70% (Probable).
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 . Induces increase in PC species with longer polyunsaturated chains than isoform 2 .
Produces a higher increase in the level of PC species containing long chains with three double bonds than isoform 1.
Subcellular locations: Endoplasmic reticulum
localized in the endoplasmic reticulum (ER) of the liver and in a lipid metabolism-rich region of the ER known as mitochondria-associated membranes . Adopts a topography within the ER membrane that positions both termini in the cytosol .
Subcellular locations: Endoplasmic reticulum membrane, Mitochondrion membrane
Found in endoplasmic reticulum where most PEMT activity is generated and in mitochondria.
Subcellular locations: Endoplasmic reticulum membrane
Primarily expressed in liver (at protein level).