Evidence for a trans-dominant regulator of purine nucleoside phosphorylase expression in rat hepatoma cells.
Somatic Cell Genet
; 9(2): 249-67, 1983 Mar.
Article
en En
| MEDLINE
| ID: mdl-6403993
ABSTRACT
Purine nucleoside phosphorylase (PNP) levels are modulated during the growth cycle of rat hepatoma cells and increase two- to three-fold as cells go from early exponential growth phase to stationary growth phase. A mutant of these hepatoma cells has been isolated which is deficient in PNP activity. Quantitative immunoprecipitation tests indicate that the decrease in enzyme activity is due to a decrease in the number of PNP molecules. The low level of PNP enzyme produced by the mutant, however, is indistinguishable from the wild-type enzyme, suggesting that the mutant may be defective in the ability to modulate PNP levels. Fusion of the mutant cells to wild-type parental cells results in hybrids that express the mutant phenotype. Segregants that arise from the hybrids show chromosome loss and reexpression of the wild-type parental phenotype, the mutant parental phenotype, and a 2S wild-type phenotype. These indicate the following about the defect in modulation in the mutant PNP-100 (1) it is trans dominant to the wild-type; (2) its effect is negative; (3) some genomic element is required for its continued effect; and (4) it does not act by obliterating its functioning counterpart in hybrid cells.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Pentosiltransferasa
/
Genes Reguladores
/
Purina-Nucleósido Fosforilasa
/
Genes Dominantes
/
Neoplasias Hepáticas Experimentales
Límite:
Animals
Idioma:
En
Revista:
Somatic Cell Genet
Año:
1983
Tipo del documento:
Article