/sup 31/P NMR spectra of rod outer segment and sarcoplasmic reticulum membranes show no evidence of immobilized components due to lipid-protein interactions
/sup 31/P NMR studies of rod outer segment (ROS) and sarcoplasmic reticulum (SR) membranes have been performed under conditions where broad and narrow spectral components can be clearly resolved. For the codispersions of DSPC and DOPC in the mixed-phase region at 22/sup 0/C, the /sup 31/P NMR spectra consist of a superposition of a broad component and a narrow, axially symmetric component, due to coexisting solid and liquid-crystalline domains, which are in slow exchange on the /sup 31/P NMR time scale. The /sup 31/P NMR spectra of the native ROS and SR membranes, however, consist of only a narrow component, to within experimental error, indicating that most or all of the phospholipids are in the liquid-crystalline (L/sub ..cap alpha../ phase at 22/sup 0/C. It is estimated that at most 10% of the phospholipids in the ROS and SR membranes could give rise to broad /sup 31/P NMR spectral components, similar to those seen for anhydrous or solid-phase lipids, corresponding to approx. 7 phospholipids/rhodopsin molecule and approx. 11 phospholipids/Ca/sup 2 +/-ATPase molecule, respectively.
- Research Organization:
- Univ. of Virginia, Charlottesville (USA)
- OSTI ID:
- 6602554
- Journal Information:
- Biochemistry; (United States), Vol. 25:13
- Country of Publication:
- United States
- Language:
- English
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