Transmembrane Ca2+ gradient-mediated change of fluidity in the inner layer of phospholipids modulates Ca(2+)-ATPase of sarcoplasmic reticulum.
Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without transmembrane Ca2+ gradient have been prepared. Different fluorescence probes (DPH, TMA-DPH and n-AS), were used to determine the effect of transmembrane Ca2+ gradient on the lipid fluidity both in outer and inner layer of Ca(2+)-ATPase-containing SR vesicles. The results showed that transmembrane Ca2+ gradient could significantly decrease the fluidity of the inner layer of SR membrane, while no obvious change was monitored in the outer layer. This may be deduced that Ca(2+)-ATPase might be modulated mainly by the transmembrane Ca2+ gradient-mediated alteration of physical state of phospholipid in the inner layer of SR membrane.
National Laboratory of Biomacromolecules, Academia Sinica, Beijing, China.
Y P
YP
Tu
H
H
Xu
F Y
FY
Yang
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D005456:Fluorescent Dyes; D007425:Intracellular Membranes / Q000201:enzymology; D008051:Lipid Bilayers / Q000378:metabolism; D008560:Membrane Fluidity / Q000187:drug effects / Q000502:physiology*; D010743:Phospholipids / Q000378:metabolism*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*
D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010743:Phospholipids; D000252:Calcium-Transporting ATPases; D002118:Calcium