sodium-dodecyl-sulfate and alpha-cyano-4-hydroxycinnamate

Biochemical studies were conducted to determine the location of a putative lactate transport protein in rat skeletal muscle plasma membranes (PM). PM (50-100 micrograms protein) were incubated with [U-14C] L(+)-lactate, in the presence or absence of unlabeled monocarboxylates or potential inhibitors, after which proteins were separated by SDS-PAGE. Gel slices (2 mm) were cut and analyzed for 14C. [U-14C] L(+)-lactate was bound to plasma membranes in the 30 to 40 kDa molecular mass range. Binding of [U-14C] L(+)-lactate was inhibited by N-ethylmaleimide, unlabeled L-lactate and pyruvate, and in a dose dependent manner by alpha-cyano-4-hydroxycinnamate (r = 0.995), but not by cytochalasin-B. The inhibition of [U-14C] L(+)-lactate binding was similar to the inhibition of lactate transport. Therefore the transport of L(+)-lactate across skeletal muscle plasma membranes involves a polypeptide of 30 to 40 kDa.

Topics: Animals; Carbon Radioisotopes; Carboxylic Acids; Carrier Proteins; Coumaric Acids; Cytochalasin B; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Ethylmaleimide; Lactates; Membrane Proteins; Molecular Weight; Monocarboxylic Acid Transporters; Muscle, Skeletal; Protein Binding; Pyruvates; Rats; Sarcolemma; Sodium Dodecyl Sulfate