Fig. 2. Tissue expression and membrane-binding properties of MIB. (A) Rat tissues were analyzed by SDS-PAGE and subsequent immunoblotting using anti-MIB and anti-TOM40 antibodies. (B) Subcellular fractionation of rat liver MIB. Rat liver was fractionated under isotonic buffer containing 150 mM NaCl into mitochondrial (mt), microsomal (ms) and cytosolic (cyt) fractions (20 µg per well), which were analyzed by SDS-PAGE and subsequent immunoblotting using anti-MIB, TOM40 (mitochondrial marker), calnexin (ER marker), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH; cytosolic marker). (C) Sucrose-density-gradient-centrifugation profiles of rat liver post-nuclear membrane fraction (membrane) and mitochondrial fraction (mt). The post nuclear fraction or isolated mitochondria was subjected to sucrose-gradient centrifugation at 77,600 g, for 3 hours as described in Materials and Methods.