ATP‐dependent Ca2+ transport in vesicles isolated from the bile canalicular region of the hepatocyte plasma membrane

Abstract

Three plasma membrane subfractions have been isolated and characterized from rat liver cells. The high affinity Ca2+‐stimulated ATPase is highly enriched in the bile canalicular subfraction. Taking into account cross‐contamination by the blood sinusoidal and lateral membranes it is suggested that the high‐affinity Ca2+ ‐ATPase is located exclusively in this fraction. The high‐affinity Ca2+‐ATPase is coupled to Ca2+ transport, is calmodulin‐insensitive, sensitive to vanadate under appropriate experimental conditions and is strongly inhibited by La3+. In the presence of Ca2+ and ATP the ATPase forms a phosphorylated intermediate of molecular mass about 200 kDa. Copyright © 1985, Wiley Blackwell. All rights reserved