EFFECTS OF PHOSPHATIDYLCHOLINE FATTY ACYL CHAIN-LENGTH ON CALCIUM-BINDING AND OTHER FUNCTIONS OF THE (CA2+-MG2+)-ATPASE
Starling, AP; East, JM; Lee, AG
| HERO ID | 4936324 |
|---|---|
| In Press | No |
| Year | 1993 |
| Title | EFFECTS OF PHOSPHATIDYLCHOLINE FATTY ACYL CHAIN-LENGTH ON CALCIUM-BINDING AND OTHER FUNCTIONS OF THE (CA2+-MG2+)-ATPASE |
| Authors | Starling, AP; East, JM; Lee, AG |
| Journal | Biochemistry |
| Volume | 32 |
| Issue | 6 |
| Page Numbers | 1593-1600 |
| Abstract | The ATPase activity of the (Ca2+-Mg2+)-ATPase purified from skeletal muscle sarcoplasmic reticulum and reconstituted into phosphatidylcholine bilayers of defined composition depends on the fatty acyl chain length of the surrounding phospholipid. The stoichiometry of Ca2+ binding to the ATPase is also sensitive to fatty acyl chain length, changing from the normal two Ca2+ ions bound per ATPase molecule to one Ca2+ ion bound for the ATPase reconstituted with phosphatidylcholines of chain lengths C12, C14, or C24. For the ATPase reconstituted with mixtures of phosphatidylcholines where one phosphatidylcholine supports a Ca2+ binding stoichiometry of two and the other a stoichiometry of one, a highly cooperative change in binding stoichiometry with change in phospholipid composition is observed, suggesting that the effects of phospholipids follow from binding to a large number of sites at the lipid-protein interface of the ATPase. For the ATPase reconstituted with either 1-myristoyl-2-oleoylphosphatidylcholine or 1-oleoyl-2-myristoylphosphatidylcholine, the stoichiometry of Ca2+ binding is the normal two per ATPase molecule. Effects of short-chain phosphatidylcholines on Ca2+ binding stoichiometry and on ATPase activity can be reversed by addition of androstenol, oleic acid, methyl oleate, or oleyl alcohol but these molecules have no effect on the ATPase reconstituted with dinervonylphosphatidylcholine (C24:1). For the ATPase reconstituted with phosphatidylcholines with chain lengths between C16 and C22, release of the two bound Ca2+ ions is sequential, with release of the second Ca2+ being inhibited by high concentrations of Ca2+ in the bathing medium. For the ATPase reconstituted with phosphatidylcholines of chain lengths C14 or C24, release of the single bound Ca2+ is only slightly inhibited by the presence of Ca2+ in the medium. For the ATPase reconstituted with phosphatidylcholines of chain lengths between C16 and C24, removal of bound Ca2+ results in a decrease in tryptophan fluorescence intensity, whereas for the ATPase reconstituted with phosphatidylcholines of chain lengths C12 or C14, removal of bound Ca2+ results in an increase in tryptophan fluorescence intensity. In mixtures of phosphatidylcholines, changes in the tryptophan response mirror changes in Ca2+ binding stoichiometry. |
| Doi | 10.1021/bi00057a025 |
| Wosid | WOS:A1993KM70300025 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |