In this work, an ion transporting channel protein has been isolated and purified from the rat liver microsomes by using the water-ethanol extraction method. The electrophysiological and regulatory properties of the protein were studied. It was shown that the minimum conductance value of the channel is 10pS. When reconstructed into the BLM, the protein formed ion channels with a multilevel conductance. The conductance of this channel protein is divided into different levels. The conductance value of clusters is a multiple of that of the single protein channel. Volt-ampere characteristics (VAC) recorded in the voltage range from -100mV to 100mV indicates the potential-sensitivity of the microsomal channel protein. The data obtained suggest that the protein isolated from microsomes is not selective for K+ ions, which may be due to its localization and its participation in processes mediated by transport of not only potassium, but also other monovalent ions. The observed effects of ATP and ADP on activity of the channel isolated from microsomes of rat hepatocytes make it possible to classify it as a member of ATP-sensitive protein family. The inhibitory effect of 5-hydroxydecanoate on the studied channel protein indicates that mitoKATP like proteins, in addition to mitochondria, can also be localized in the endoplasmic reticulum.
mitochondria, microsomes, black lipid membranes, ATP-dependent potassium channels, 5-hydroxydecanoate
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