SEQUENTIAL CONTROL OF HEXOKINASE IN ASCITES CELLS

Studies of transient changes in the total rate of glucose phosphorylation compared with the changes in glucose-6-phosphate (G6P), ATP, ADP and fructose diphosphate (FDP) have suggested a sequence of operation of control mechanisms following the addition of glucose to ascites cells. These are: (a) a rapid rate of glucose phosphorylation (50% Vmax) for 15 sec. which appears to be independent of feedback inhibition by G6P which accumulates to inhibitory concentrations within 3 sec.; (b) a release of bound hexokinase by G6P; (c) a slow rate of glucose phosphorylation under feedback control by G6P; (d) the possible involvement of FDP inhibition; this control may depend on Mg++ availability. © 1969.