title: Composition and physical properties of lipids from plasma membranes of dog kidney.
abstract: Lipid composition, physical state of major phospholipid classes and transbilayer migration of phosphatidylcholine have been determined in plasma membranes of the dog kidney. The lipid composition of brush-border membranes markedly differs from that of antiluminal membranes with respect to: (a) the total phospholipid content; (b) the cholesterol to phospholipid ratio (C/P); (c) the distribution of the major phospholipid classes. Sphingomyelin present in large amounts in both luminal and antiluminal membranes extracts exhibits a transition of phase between 20 and 44 degrees C approximately. In the range of temperature studied (5-55 degrees C) no phase transitions were detected for the other phospholipid species. Our data suggest that: (1) at physiological temperature the higher C/P ratio of brush-border membranes is in large part responsible for their lower fluidity; (2) both the relatively low cholesterol and high sphingomyelin contents contribute to the thermotropic transitions observed in intact membranes. Finally transbilayer migration of phosphatidylcholine in brush-border membranes is a very slow process with a half time of 6.5 h at 37 degrees C which compares with that of other biological membranes.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D002784:Cholesterol / Q000302:isolation & purification; D004285:Dogs; D005227:Fatty Acids / Q000302:isolation & purification; D005260:Female; D007668:Kidney / Q000032:analysis*; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000302:isolation & purification*; D008871:Microvilli / Q000032:analysis; D010743:Phospholipids / Q000302:isolation & purification; D013816:Thermodynamics
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D010743:Phospholipids; D002784:Cholesterol