Production of antibody against cytosolic 54kDa protein in rat liver evidence of the significant induction by a highly toxic coplanar polychlorinated biphenyl

We have reported that a 54kDa protein in rat liver cytosol is highly inducible by treatment with 3,3',4,4',5-pentachlorobiphenyl (PenCB) or 3- methylcholanthrene (MC) using SDS-polyacrylamide gel electrophoresis. Internal amino acid sequences of this protein in the rat liver were highly homologous to those of selenium binding protein (SeBP) or acetaminophen binding protein (APBP) in mouse liver cytosol. In this paper, the purification and characterization of this protein were demonstrated MC was given at a dose of 20 mg/kg for 3 consecutive days. The liver cytosolic 54kDa protein was purified twice from the MC-treated male Wistar rats by Rotofore Cell(TM) procedure to apparent single on SDS-polyacrylamide gel electrophoresis, and the rabbit antiserum against this protein was obtained. Male Wistar rats were given PenCB in corn oil at a single dose of 25 mg/kg i.p. The liver cytosol was prepared on the 5th day after the treatment and subjected to immunoblot analysis. The 54kDa protein was markedly induced in the liver cytosol of PenCB-treated rats. Immunoblot analysis after two- dimensional gel electrophoresis suggested that there could be isoforms of 54kDa protein. The induction of the 54kDa protein with PenCB was assumed to be mediated through Ah-receptor. The physiological role of the 54kDa protein was discussed together with SeBP and APBP, the role of which has not yet been elucidated.