Total membranes were prepared by taking approximately 500 mg of liver tissue cut into small pieces and homogenized in ice cold lysis buffer (5 mM Tris-pH7.5, 250 mM sucrose with protease inhibitors) by a dounce homogenizer times 10 strokes. Samples were then subjected to centrifugation – 1300 g for 10 minutes at 4°C. The supernant was saved and the pellet was resuspended and again subjected to dounce homogenization times 10 strokes then centrifuged 1000 g for 10 minutes at 4°C. This step was repeated twice each time with the supernant being collected and kept on ice. The supernants were then pooled and subjected to ultracentrifugation at 100,000 g for 60 minutes at 4°C. The supernant was removed and the pellet was resuspended in lysis buffer. Plasma membranes were prepared as previously described [31]. Protein sample concentrations were then determined by Bio-Rad protein colormetric assay per manufacturer's protocol (BioRad, Hercules, CA, USA). 50 μg of membrane proteins were then resolved on 7.5% SDS acrylamide gel.