The biochemical determinants of hypoxanthine uptake in Novikoff rat hepatoma cells.
The rate with which Novikoff rat hepatoma cells took up exogenous hypoxanthine increased sharply towards the end of the logarithmic growth phase, remained high for several hours into the stationary phase, and then decreased again. In an effort to account for these phenomena, several biochemical parameters were monitored during culture growth: the activities of the hypoxanthine transporter, of hypoxanthine phosphoribosyltransferase, and of P-Rib-PP synthetase; and the intracellular concentrations of ATP and P-Rib-PP. All of these parameters remained virtually constant during growth of the culture, except for P-Rib-PP, which increased greater than 10-fold in a pattern similar to that for hypoxanthine uptake. The activities of the transporter, synthetase, and phosphoribosyltransferase remained stable over 7 h of treatment with cycloheximide.
D000818:Animals; D001692:Biological Transport; D002455:Cell Division; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D019271:Hypoxanthine; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism; D007042:Hypoxanthines / Q000378:metabolism*; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000378:metabolism* / Q000503:physiopathology; D010754:Phosphoribosyl Pyrophosphate / Q000378:metabolism; D051381:Rats; D012268:Ribose-Phosphate Pyrophosphokinase / Q000378:metabolism
D007042:Hypoxanthines; D003609:Dactinomycin; D019271:Hypoxanthine; D010754:Phosphoribosyl Pyrophosphate; D003513:Cycloheximide; D007041:Hypoxanthine Phosphoribosyltransferase; D012268:Ribose-Phosphate Pyrophosphokinase