title: Phospholipid chain immobilization and steroid rotational immobilization in acetylcholine receptor-rich membranes from Torpedo marmorata.
abstract: 1. The ESR spectra of both phosphatidylcholine and phosphatidylethanolamine spin labels reveal an immobilized lipid component (tau R greater than or equal to 50 ns), in addition to a fluid component (tau R approximately 1 ns), in acetylcholine receptor-rich membranes prepared from Torpedo marmorata electroplax according to the method of Cohen et al. (Cohen, J.B., Weber, M., Huchet, M. and Changeux, J.-P. (1972) FEBS Lett. 26, 43--27). 2. The ESR spectra of the androstanol spin label display a component corresponding to molecules which are immobilized with respect to rotation about the long molecular axis (tau R greater than or equal to 50 ns), in addition to the fluid lipid bilayer component in which the molecules are rotating rapidly about their long axes (tau R approximately 1 ns). This immobilized component is observed throughout the temperature range 2--22 degrees C, at an approximately constant relative intensity of approx. 45% of the total, which is quantitatively the same as previously observed with fatty acid spin labels.
mesh_terms: D000732:Androstanols; D000818:Animals; D002462:Cell Membrane / Q000032:analysis*; D004557:Electric Organ / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D005399:Fishes / Q000033:anatomy & histology; D010713:Phosphatidylcholines / Q000032:analysis; D010714:Phosphatidylethanolamines / Q000032:analysis; D011950:Receptors, Cholinergic / Q000032:analysis*; D013113:Spin Labels; D013696:Temperature
chemical_list: D000732:Androstanols; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D011950:Receptors, Cholinergic; D013113:Spin Labels