title: In vivo regulation of phosphorylation level and activity of phosphofructokinase by serotonin in Fasciola hepatica.
abstract: The level of phosphorylation and activation of phosphofructokinase by serotonin (5-hydroxytryptamine) was studied in intact liver flukes Fasciola hepatica. The enzyme was immunoprecipitated with antiserum prepared against pure enzyme from the liver flukes. The resuspended immunoprecipitated enzyme retained most of its original activity and its kinetic properties. The level of phosphorylation was determined by a "back phosphorylation" technique. According to this technique, the immunoprecipitated phosphofructokinase was phosphorylated with the catalytic subunit of pure cAMP-dependent protein kinase. Incubation of intact liver flukes with serotonin caused an increase in the level of enzyme phosphorylation which was concomitant with an increase in enzyme activity. The level of phosphorylation was increased by 0.08 mol per protomer as a result of maximal activation by serotonin. It is proposed that phosphorylation plays, at least in part, a functional role in the regulation of phosphofructokinase from the liver fluke F. hepatica under in vivo conditions.
authors.affiliation: Department of Pharmacology, Stanford University School of Medicine, California 94305.
authors.forename: E S
authors.initials: ES
authors.lastname: Kamemoto
authors.forename: L
authors.initials: L
authors.lastname: Lan
authors.forename: T E
authors.initials: TE
authors.lastname: Mansour
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation / Q000187:drug effects; D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D005210:Fasciola hepatica / Q000187:drug effects / Q000201:enzymology*; D007163:Immunosorbent Techniques; D007700:Kinetics; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*; D013053:Spectrophotometry
chemical_list: D012701:Serotonin; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011494:Protein Kinases; D010732:Phosphofructokinase-1