Isolation and Functional Reconstitution of the Dicarboxylate Carrier from Bovine Liver Mitochondria

Abstract

In order to understand the structure and function relationship of mitochondrial transporters, recent efforts have been focused on isolation of the individual carriers and their functional reconstitution into proteoliposomes (for review see Nałęcz , 1986). In line with these studies we reported a successful purification by affinity chromatography of the dicarboxylate carrier from bovine heart mitochondria (Szewczyk et al., 1987). In general, heart mitochondria are considered optimal for studies on purification of the inner membrane proteins. This comes from the fact that the cristae/matrix ratio of these organelles is exceptionally high (more membranes per unit of weight of the mitochondrial preparation) and, in addition, from that the activity of proteolytic enzymes in heart homogenates is relatively low. On the other hand, however, it is known that the mitochondrial dicarboxylate carrier activity is much higher in liver than in heart (Sluse et al., 1971). Although it has not been clarified whether this is due to difference in total amount of the carrier protein in mitochondria, we found that only very little of the translocator protein could actually be isolated from heart (Szewczyk et al., 1987). Thus it seemed logical to try to isolate the dicarboxylate carrier from liver mitochondria.