Freeze-fracture analysis of plasma membrane cholesterol in Duchenne muscle.
We estimated cholesterol in Duchenne muscle plasma membrane using the sterol-specific ligand digitonin. In measuring the extent of digitonin-cholesterol complex formation with freeze-fracture electron microscopy, we found a significantly greater proportion of surface area taken up by complexes in Duchenne muscle (60% +/- 9%) than in controls (36% +/- 4%). This finding suggests that a population of Duchenne muscle fibers has a higher concentration of cholesterol in the plasma membrane. Membrane cholesterol is known to affect membrane deformability and the activity of membrane-bound enzymes and transport proteins; thus a difference in membrane cholesterol might account for structural and functional abnormalities in Duchenne plasma membrane.
D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002784:Cholesterol / Q000378:metabolism*; D004072:Digitonin / Q000378:metabolism; D005614:Freeze Fracturing; D006801:Humans; D008854:Microscopy, Electron; D009132:Muscles / Q000378:metabolism* / Q000648:ultrastructure; D009136:Muscular Dystrophies / Q000378:metabolism* / Q000473:pathology
D002784:Cholesterol; D004072:Digitonin