| Autor: |
John D. Hayes, D J Judah, D G Petersson, T Nguyen, G.E. Neal |
| Rok vydání: |
1994 |
| Předmět: |
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| Zdroj: |
Journal of Biological Chemistry. 269:20707-20717 |
| ISSN: |
0021-9258 |
| DOI: |
10.1016/s0021-9258(17)32050-1 |
| Popis: |
Fetal rat liver possesses substantial levels of glutathione S-transferase (GST) activity toward aflatoxin B1-8,9-epoxide. The enzyme responsible for this activity is an Alpha-class GST heterodimer comprising Yc1 and Yc2 subunits. The cDNAs encoding these polypeptides have been cloned and shown to share approximately 91% identity over 920 base pairs, extending from nucleotide -23 to the AATAAA polyadenylation signal. GST Yc2Yc2 expressed in Escherichia coli was found to exhibit 150-fold greater activity toward aflatoxin B1-8,9-epoxide than GST Yc1Yc1. Comparison between the structures of Alpha-class GST suggests that tyrosine at residue 108 and/or aspartate at residue 208 is responsible for the high aflatoxin B1 detoxication capacity of Yc2. Immunoblotting and enzyme assays have shown that liver from adult female rats contains about 10-fold greater levels of Yc2 than is found in liver from adult male rats. This sex-specific expression of Yc2 in adult rat liver may contribute to the relative insensitivity of female rats to aflatoxin B1. Dietary administration of oltipraz, a synthetic antioxidant which protects against aflatoxin-hepatocarcinogenesis, serves as an inducer of GST Yc2. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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