THE ATP-DEPENDENT POTASSIUM CHANNEL FROM RAT-LIVER MITOCHONDRIA .1. ISOLATION, PURIFICATION, AND RECONSTITUTION IN A BILAYER-LIPID MEMBRANE

The ATP-dependent potassium channels have been isolated from tile rat liver mitochondrial membrane and purified without a detergent as a 55- kD protein. incorporation of this protein into a bilayer lipid membran e leads to the formation of the potassium selective ionic channels. Th e conductance of the open state of the single Elementary channel is 10 pS at 100 mM KCI. The probability of the open state increases at high er DM values. The plot of the integral condactance of the modified mem brane is directly proportional to K+ concentration. The integral condu ctance of the membrane versus protein concentration has sigmoidal form . It means that the channel is assembled of several protein subunits. The ATP at physiological concentrations (1-3 mM) inhibited conductance of these channels. Our results suggest that mitochondrial 55-kD prote in is one of a family of ATP-sensitive K+ channels.