Muscle aldolase decreases muscle FBPase sensitivity toward AMP inhibition.

Muscle aldolase bound to muscle FBPase (K(d) = 8.7 microM) decreases the latter's sensitivity towards AMP inhibition. I(0.5) of muscle FBPase was increased from 0.06 microM to 0.65 microM when determined in the presence of 10 microM of muscle aldolase. In the presence of 10 microM of liver aldolase I(0.5) of liver FBPase was increased only twofold, from 11.0 microM to 21.7 microM. The effect of muscle aldolase on liver FBPase and liver aldolase on muscle FBPase is rather negligible. Aldolase slightly affected interaction of FBPase with magnesium ions decreasing K(a) and Hill constant (n). No effect of aldolase on FBPase pH optimum was observed. Copyright 2000 Academic Press.