Phosphofructokinase from mollusc muscle is activated by phosphorylation.
Phosphofructokinase was purified from muscle tissue of two different molluscs, edible snails, Helix pomatia (gastropoda), and mussels, Mytilus edulis (bivalvia). Under denaturing conditions, both enzymes had a molecular mass of 82 kDa. In the presence of ATP-Mg2+, the enzymes were rapidly phosphorylated in vitro by the catalytic subunit of cyclic AMP (cAMP)-dependent protein kinase purified from snail muscle and also by the C subunit of protein kinase from bovine heart. The extent of phosphorylation was 0.6 and 0.5 phosphate residues per subunit for the snail and the mussel phosphofructokinase, respectively. Phosphorylation of both phosphofructokinases effected a decrease in ATP inhibition at neutral or slightly acidic pH values and increased the affinity for fructose 6-phosphate. The resulting activation in the presence of suboptimum fructose 6-phosphate concentrations was more distinct for the snail enzyme. In addition, phosphorylated phosphofructokinase from mussels exhibited a marked increase in Vmax when activated by either 5'-AMP or fructose 2,6-bisphosphate.
Biethinger
M
M
Faculty of Biology, University of Konstanz, Germany.
Hoffmann
R
R
Hofer
H W
HW
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D000242:Cyclic AMP / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005635:Fructosediphosphates / Q000494:pharmacology; D005636:Fructosephosphates / Q000378:metabolism; D006372:Helix, Snails / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011489:Protein Denaturation; D011494:Protein Kinases / Q000378:metabolism
D005635:Fructosediphosphates; D005636:Fructosephosphates; D010750:Phosphoproteins; D000249:Adenosine Monophosphate; C027618:fructose-6-phosphate; C027652:fructose 2,6-diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011494:Protein Kinases; D010732:Phosphofructokinase-1