Partial purification and properties of a non-ligandin (3H) 3-methylcholanthrene binding protein from liver cytosol |
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Authors: | R Filler K S Morey G Litwack |
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Institution: | Fels Research Institute and Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pa. 19140 USA |
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Abstract: | (3H) 3-Methylcholanthrene binds to a macromolecule in addition to the previously reported binding to ligandin in liver cytosol. The properties of this second molecule are identical to those of the glucocorticosteroid receptor (Binder II) through 400 fold purification over the cytosol proteins (elution position from DEAE-Sephadex A-50 columns, molecular weight by gel filtration and pI value by isoelectrofocusing). The carcinogen, probably a metabolite, binds very strongly or covalently to the macromolecule , but non-covalently in the absence of microsomes. Large amounts of unlabeled carcinogen administered do not compete significantly with subsequent (3H) dexamethasone binding to the hormone receptor fraction . Methylcholanthrene and dexamethasone do not compete for binding sites on isolated unlabeled Binder II leading to the conclusion that the glucocorticosteroid receptor and the methylcholanthrene binding protein are distinct entities. |
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Keywords: | To whom correspondence regarding this paper should be addressed |
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