Nonhistone protein BA is a glutathione S-transferase localized to interchromatinic regions of the cell nucleus.
J Cell Biol
; 102(2): 600-9, 1986 Feb.
Article
em En
| MEDLINE
| ID: mdl-2935545
ABSTRACT
A DNA-binding nonhistone protein, protein BA, was previously demonstrated to co-localize with U-snRNPs within discrete nuclear domains (Bennett, F. C., and L. C. Yeoman, 1985, Exp. Cell Res., 157379-386). To further define the association of protein BA and U-snRNPs within these discrete nuclear domains, cells were fractionated in situ and the localization of the antigens determined by double-labeled immunofluorescence. Protein BA was extracted from the nucleus with the 2.0 M NaCl soluble chromatin fraction, while U-snRNPs were only partially extracted from the 2.0 M NaCl-resistant nuclear structures. U-snRNPs were extracted from the residual nuclear material by combined DNase I/RNase A digestions. Using an indirect immunoperoxidase technique and electron microscopy, protein BA was localized to interchromatinic regions of the cell nucleus. Protein BA was noted to share a number of chemical and physical properties with a family of cytoplasmic enzymes, the glutathione S-transferases. Comparison of the published amino acid composition of protein BA and glutathione S-transferases showed marked similarities. Nonhistone protein BA isolated from saline-EDTA nuclear extracts exhibited glutathione S-transferase activity with a variety of substrates. Substrate specificity and subunit analysis by SDS polyacrylamide gel electrophoresis revealed that it was a mixture of several glutathione S-transferase isoenzymes. Protein BA isolated from rat liver chromatin was shown by immunoblotting and peptide mapping techniques to be two glutathione S-transferase isoenzymes composed of the Yb and Yb' subunits. Glutathione S-transferase Yb subunits were demonstrated to be both nuclear and cytoplasmic proteins by indirect immunolocalization on rat liver cryosections. The identification of protein BA as glutathione S-transferase suggests that this family of multifunctional enzymes may play an important role in those nuclear domains containing U-snRNPs.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas Cromossômicas não Histona
/
Núcleo Celular
/
Glutationa Transferase
Limite:
Animals
Idioma:
En
Ano de publicação:
1986
Tipo de documento:
Article