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Updated: Mar 31, 2026

Purification of the Sarco-Endoplasmic Reticulum Ca2+-ATPase from Rabbit Muscle
Published on: March 21, 2025
Two populations of phospholipids exist in sarcoplasmic reticulum and in recombined membranes containing Ca-ATPase
Abstract:
Phosphorus nuclear magnetic resonance spectra of sarcoplasmic reticulum membranes from rabbit muscle and of recombined membranes containing the calcium-dependent adenosinetriphosphatase (Ca-ATPase) of sarcoplasmic reticulum reveal two distinguishable, overlapping resonances. One resonance resembles a normal phospholipid bilayer resonance, and the other is much broader. The broader component is not seen in protein-free phospholipid vesicles. In recombined membranes of the Ca-ATPase, the intensity found in the broad component was proportional to the concentration of protein in the vesicles. The two-component spectra are interpreted to arise from at least two different domains of phospholipids, one of which is motionally restricted by the Ca-ATPase. Phospholipids exchange between these two domains at a rate less than 10(3) s-1. A model for protein-lipid interactions in membranes containing the Ca-ATPase is proposed in which some of the phospholipid head groups of the membrane interact directly with the protein.
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