title: Properties and topology of enzymes methylating phosphatidylethanolamine to phosphatidylcholine in sarcoplasmic reticulum.
abstract: 1. The synthesis of phosphatidylcholine (PC) by stepwise methylation of phosphatidylethanolamine (PE) is carried out by two enzymes in sarcoplasmic reticulum (SR) membrane of rabbit fast-twitch skeletal muscles. 2. Two methyltransferases (Met I and Met II) have a different pH optimum and affinity for methyl donor--S-adenosyl-L-methionine (SAM). 3. Met I is an integral SR membrane protein which active site faces the cytoplasmic surface of the membrane. 4. Met II is a peripheral, loosely bound protein, localized mainly on the extracytoplasmic (luminal) part of the SR membrane.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D007700:Kinetics; D008780:Methyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology*; D050918:Phosphatidylethanolamine N-Methyltransferase; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*
chemical_list: D008780:Methyltransferases; D050918:Phosphatidylethanolamine N-Methyltransferase