title: The mapping of three subfractions of endoplasmic reticulum membranes isolated from L-929 cells by the use of spin probes.
abstract: This paper concerns the estimation of microviscosity parameters in smooth, light rough and heavy rough endoplasmic reticulum subfractions isolated from L-929 cells. Electron spin resonance using three probes was utilized in order to make estimations of rotational correlation times. The highest microviscosity was found in the smooth fraction. The lipid bilayer is less viscous and the annular one more rigid in heavy rough compared to light rough membranes. The individual membrane subfractions differ with regard to their 'portrait' of thermoinduced structural transitions. The highest number of such transitions was detected in smooth membranes. There were no low-temperature transitions (relative to physiological temperature) or common thermoinduced structural rearrangements of the lipids in the heavy rough subfraction, a membrane fraction characteristic of transformed cells. The results show that each membrane subfraction is characterized by an intrinsic series of thermoinduced structural transitions, which, in combination with an estimation of microviscosity, yields a 'portrait' of the structural state of the membrane lipids.
authors.affiliation: Institute of Chemical Physics, USSR Academy of Sciences, Moscow.
authors.forename: E L
authors.initials: EL
authors.lastname: Maltseva
authors.forename: N P
authors.initials: NP
authors.lastname: Palmina
authors.forename: I F
authors.initials: IF
authors.lastname: Pryme
mesh_terms: D000818:Animals; D002458:Cell Fractionation / Q000379:methods; D002499:Centrifugation, Density Gradient; D004578:Electron Spin Resonance Spectroscopy; D004721:Endoplasmic Reticulum / Q000737:chemistry*; D006358:Hot Temperature; D007425:Intracellular Membranes / Q000737:chemistry*; D007739:L Cells; D008051:Lipid Bilayers / Q000737:chemistry; D051379:Mice; D013113:Spin Labels; D014783:Viscosity
chemical_list: D008051:Lipid Bilayers; D013113:Spin Labels