K+ transport in mitoplasts.
K+ transport into mitoplasts, prepared by digitonin disruption and removal of the outer membranes from rat liver mitochondria, has been studied. Unidirectional K+ influx has been measured by means of 42K, in the presence of the respiratory substrate succinate. K+ influx is inhibited by CN-, antimycin A and dicyclohexylcarbodiimide, but is insensitive to oligomycin. A linear dependence of the reciprocal of the K+ -influx rate on the reciprocal of the external K+ concentration is observed. Under the conditions studied, the apparent Km for K+ of the transport mechanism is approx. 6 mM, while the Vmax of K+ influx is approx. 5 mu mol K+/g protein per min. The rate of K+ influx increases with increasing external pH over the range from 6.8 to 8.0. The observed kinetics, pH dependence and inhibitor sensitivity are essentially similar to previously reported characteristics of K+ transport into intact rat liver mitochondria. It is concluded that the outer mitochondrial membrane does not not have a role in controlling K+ flux into rat liver mitochondria.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003486:Cyanides / Q000494:pharmacology; D007700:Kinetics; D008930:Mitochondria, Liver / Q000378:metabolism*; D010101:Oxygen Consumption; D011188:Potassium / Q000378:metabolism*; D051381:Rats
D003486:Cyanides; D000244:Adenosine Diphosphate; D011188:Potassium