In vitro binding of labeled 20-methylcholanthrene to a specific cytosol-protein

Thomas J. Slaga, John D. Scribner, Jannas M. Rice

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


In vitro binding kinetics and specificity of [20-3H]methylcholanthrene ([3H]MC) interaction with mouse epidermal cytosol in the presence or absence of microsomal metabolizing systems were investigated. After an incubation period of 30 roin at 22°, the samples were dialyzed, subjected to gel filtration, ultrafiltration, and analyzed by 7 % basic polyacrylamide gel electrophoresis. A major portion of the binding appeared in a single peak on the gel which had the same mobility as bovine or mouse serum albumin. In vitro competition by other hydrocarbons or by promoters for binding of MC to this cytosol receptor protein showed an impressive correlation to carcinogenic and promoting activities. Essentially 100% of the MC bound to cytosol without a microsomal metabolizing system was non-covalent. However, binding Of MC to cytosol in the presence of microsomes plus reduced NADPH was party covalent which has previously been reported by Grover and Sims and Meunier and Chaveau. When bovine (BSA) or mouse serum albumin (MSA) was incubated with radioactive MC in the presence of competing non-radioactive carcinogens or promoters, little or no inhibition of binding was found. The finding that both a powerful tumor promoter and a strong carcinogen are competitors for the specific MC binding to the cytosol receptor protein indicates that it may represent a critical interaction for the promoting stage of chemical carcinogenesis in mouse skin.

Original languageEnglish (US)
Pages (from-to)51-62
Number of pages12
JournalChemico-Biological Interactions
Issue number1
StatePublished - Jul 1973
Externally publishedYes

ASJC Scopus subject areas

  • Toxicology


Dive into the research topics of 'In vitro binding of labeled 20-methylcholanthrene to a specific cytosol-protein'. Together they form a unique fingerprint.

Cite this