Ribose 1,5-bisphosphate inhibits fructose-1,6-bisphosphatase in rat kidney cortex.
Fructose-1,6-bisphosphatase is one of the regulatory enzymes of gluconeogenesis in kidney cortex. The effect of ribose 1,5-bisphosphate on fructose-1,6-bisphosphatase purified from rat kidney cortex was studied. Rat kidney cortex, fructose-1,6-bisphosphatase exhibited hyperbolic kinetics with regard to its substrate, but the activity was inhibited by ribose 1,5-bisphosphate at nanomolar concentrations. The inhibitory effect of ribose 1,5-bisphosphate on the fructose-1,6-bisphosphatase was enhanced in the presence of AMP, one of the inhibitors of fructose-1,6-bisphosphatase. Fructose-2,6-bisphosphate, which is an inhibitor of fructose-1,6-bisphosphatase, inhibited rat kidney cortex fructose-1,6-bisphosphatase activities at a low concentration of fructose-1,6-bisphosphate but a high concentration of fructose-1,6-bisphosphate relieved fructose-1,6-bisphosphatase from fructose-2,6-bisphosphate-dependent inhibition. On the contrary, fructose-1,6-bisphosphate was not effective for the recovery of fructose-1,6-bisphosphatase from ribose 1,5-bisphosphate-dependent inhibition. These results suggest that ribose 1,5-bisphosphate is a potent inhibitor and is involved in the regulation of fructose-1,6-bisphosphatase in rat kidney cortex.
Ozaki
I
I
Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Mitsui
Y
Y
Sugiya
H
H
Furuyama
S
S
D000818:Animals; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007672:Kidney Cortex / Q000201:enzymology*; D010428:Pentosephosphates / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D010428:Pentosephosphates; C050562:ribose-1,5-bisphosphate; D006597:Fructose-Bisphosphatase