Lipid requirement of the vanadate effect on the binding of calcium and ATP to the calcium transport ATPase of the sarcoplasmic reticulum.
Lipid deprivation of the sarcoplasmic reticulum calcium-transport ATPase neither affects the enzyme's affinity for ATP nor that of calcium. In contrast, vanadate binding is almost completely abolished. Lipid substitution by oleic acid which at a ratio of 0.3 mg/mg protein completely reactivates the calcium-dependent ATP hydrolysis restores vanadate binding. Concomitantly the mutual interactions between vanadate and calcium or ATP and ADP, respectively are restored. The vanadate-induced disappearance of the enzyme's ATP binding sites as well as its high-affinity binding sites for calcium follow the same time course. Conversely, the displacement of vanadate by calcium proceeds in parallel with the recovery of ADP binding. In lipid-restituted preparations as well as in native membranes vanadate induces the disappearance of external high-affinity and simultaneously the appearance of internal low-affinity calcium binding sites.
Medda
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Hasselbach
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D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D008055:Lipids / Q000172:deficiency / Q000494:pharmacology*; D008563:Membrane Lipids / Q000378:metabolism; D009132:Muscles / Q000201:enzymology / Q000378:metabolism; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
D008055:Lipids; D008563:Membrane Lipids; D014639:Vanadium; D014638:Vanadates; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D002118:Calcium