Ionophore properties of brain Na+, K+-ATPase on planar lipid membranes
Fiziologicheskii Zhurnal 29(6): 700-709
ISSN/ISBN: 0201-8489 PMID: 6317472 Accession: 043467905
Ionophore properties of highly purified Na+,K+-ATPase preparations from the cattle brain were studied on biomolecular lipid membranes (BLM) of various phospholipid composition and with a low cholesterol content. The enyzme was isolated in the presence of lipids from germinated soybeans (azolectin) and BLM were modified by fusion with a bilayer of liposomes, to whose membranes the enzyme was introduced. Intact Na+,K+-ATPase changes the conductivity of BLM of a definite composition, inducing current fluctuations at constant voltage. Properties of the modified BLM are very close to those of the enzyme in vitro and the pump in situ, suggesting that the Na+,K+-ATPase is built into the BLM and accomplishes a definite transport function. Na+,K+-ATPase-induced current fluctuations in the BLM are evidently due to protein and lipids, especially acid phospholipids and cholesterol.