Figure 2.

Sodium dependent carnitine uptake in proteoliposomes by exosomal OCTN2. Proteoliposomes were obtained by reconstitution of exosomal protein extract as described in Materials and Methods. (a) Transport activity was started adding 50 µM ³H-carnitine to proteoliposomes and terminated at the indicated times loading the samples on cold columns containing Sephdex G-75. The uptake was measured in presence (⦁) or absence (○) of external 80 mM NaCl. (b) NaCl at the indicated concentrations was added to proteoliposomes. After 2 min of incubation, carnitine transport was started adding 50 µM ³H-carnitine and stopped after 60 min. The osmolarity of each sample was balanced by substituting the NaCl with an appropriate concentration of sucrose. The values are the mean ± SD from three experiments. (*) Significantly different as estimated by the Student’s t test (p < 0.05).