Incorporation of lipids into cellular membranes—A spin-label assay

✍ Scribed by D. Marsh; R. Pellkofer; P. Hoffmann-Bleihauer; K. Sandhoff

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 522 KB
• Volume: 122
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(82)90272-x

✦ Synopsis

A spin-label method is described for the quantitative assay of lipid incorporation into biological membranes, using computer difference spectroscopy. The incorporation of spin-labeled sphingomyelin into synaptic plasma membranes from calf brain has been studied as a function of sonication time. The spin-label ESR spectra are able to distinguish labeled sphingomyelin which is integrated into the membrane, from the unincorporated label, even if the latter cosediments with the membranes. Spectral subtraction has been used to quantitate the degree of incorporation. The percentage of incorporation increases with increasing sonication time and also with incubation after sonication. The extent of degradation of tritium-labeled sphingomyelin by the neutral sphingomyelinase present in the membrane closely correlates with the dependence of the incorporation of the spin-labeled sphingomyelin on sonication time. This illustrates the utility of the method in the study of membrane-bound, lipid-metabolizing enzymes.