Institut for Biomedicin

Mikael Esmann

Spin-label studies of lipid-protein interactions in (Na+,K+)-ATPase membranes from rectal glands of Squalus acanthias

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  • Institut for Fysiologi og Biofysik
Lipid-protein interactions in (Na+,K+)-ATPase-rich membranes from the rectal gland of Squalus acanthias have been studied by using spin-labeled lipids in conjunction with electron spin resonance (ESR) spectroscopy. Lipid-protein associations are revealed by the presence of a second component in the ESR spectra of the membranes in addition to a component which corresponds very closely to the ESR spectra obtained from dispersions of the extracted membrane lipids. This second component corresponds to spin-labeled lipids whose motion is very significantly restricted relative to that of the fluid lipids in the membrane or the lipid extract. A stoichiometry of approximately 66 lipids per 265 000-dalton protein is found for the motionally restricted component of those spin-labeled lipids (e.g., phosphatidylcholine) which show least specificity for the protein. This corresponds approximately to the number of lipids which may be accommodated within the first shell around the alpha 2 beta 2 protein dimer. A selectivity of the various spin-labeled lipids for the motionally restricted component associated with the protein is found in the following order: cardiolipin greater than phosphatidylserine approximately stearic acid greater than or equal to phosphatidic acid greater than phosphatidylglycerol approximately phosphatidylcholine approximately phosphatidylethanolamine approximately androstanol.
OriginalsprogEngelsk
TidsskriftBiochemistry
Vol/bind24
Nummer6
Sider (fra-til)1386-1393
Antal sider8
ISSN0006-2960
StatusUdgivet - 12 mar. 1985

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