Measurement of Pyruvate Transport in Mitochondria

Abstract

Mitochondria are surrounded by two membranes. The only protein known so far to modify the permeability of the outer membrane is porin. Its activity resembles that of channel (Roos et al. 1982) with an exclusion limit of about 5,000. Due to porin, the outer membrane is permeable to ions and metabolites. Several carrier systems have instead been detected in the inner mitochondrial membrane. Transport or exchange systems for phosphate, 2-oxo-monocarboxylates, glutamate,adenine nucleotides, glutamate/aspartate, dicarboxylates, tricarboxylates, 2-oxoglutarate have been demonstrated (for review see LaNoue and Schoolwerth 1979). In mitochondria the primary transport of substrates is driven by a proton gradient or a transmembrane electrical potential built up by the respiratory chain.