The modulation of Ca2+-ATPase activity of sarcoplasmic reticulum by membrane cholesterol. The effect of enzyme coupling.
The Ca2+-ATPase activity of sarcoplasmic reticulum is relatively low (less than 2 I.U.) in vesicles where enzyme activity is geared to calcium accumulation. Modulation of membrane fluidity by enriching the membrane with cholesterol has no significant effect on enzyme activity. Collapsing the Ca2+ gradient with the calcium ionophore, A23187, unmasks the inhibitory effect of membrane cholesterol on enzyme activity.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002784:Cholesterol / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology; D008560:Membrane Fluidity / Q000187:drug effects; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology*
D000001:Calcimycin; D010664:Phenylmethylsulfonyl Fluoride; D002784:Cholesterol; D000252:Calcium-Transporting ATPases; D002118:Calcium; D004229:Dithiothreitol