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Gentleman S, Abrahams SL, Mansour TE.
“Adenosine Cyclic 3',5' Monophosphate In The Liver Fluke, Fasciola Hepatics. II. Activation Of Protein Kinase By 5 Hydroxytryptamine”.
Molec. Pharmacol.. 1976;12(1):59-68.
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Abstract
ADENOSINE CYCLIC 3AKZENTEG, 5-AKZENTEG MONOPHOSPHATE (CAMP) DEPENDENT PROTEIN KINASE ACTIVITY HAS BEEN FOUND IN BOTH THE 27.000 X G PARTICULATE AND SUPERNATANT FRACTIONS OF HOMOGENATES FROM THE LIVER FLUKE, FASCIOLA HEPATICA. THE ENZYME ACTIVITY WAS 2-5 TIMES GREATER IN THE ANTERIOR END ('HEAD') OF THE FLUKE THAN IN THE POSTERIOR END. HALF MAXIMAL ACTIVATION OF THE PROTEIN KINASE IN BOTH FRACTIONS WAS OBTAINED AT 0.1-0.4 UEM CAMP. WHEN THE ENZYME WAS ASSAYED IN THE PRESENCE OF CYCLIC NUCLEOTIDE,THE APPARENT KM FOR PROTAMINE WAS 0.1 MG/ML AND THE APPARENT KM FOR MGATP WAS 20-50- UEM IN THE TWO HOMOGENATE FRACTIONS. INCUBATION OF FLUKE HEADS FOR 5 MIN WITH 1 MM 5 HYDROXYTRYPTAMINE RESULTED IN AN INCREASE IN PROTEIN KINASE ACTIVITY OF 80TH HOMOGENATE FRACTIONS WHEN ASSAYED IN THE ABSENCE OF ADDED CAMP. THE PROTEIN KINASE ACTIVITY ASSAYED IN THE PRESENCE OF 5 UEM CAMP WAS INCREASED IN THE PARTICULATE FRACTION AND DECREASED IN THE SUPERNATANT FRACTION. THE DEGREE OF ACTIVATION OF THE ENZYME BY THE CYCLIC NUCLEOTIDE WAS MARKEDLY REDUCED IN BOTH HOMOGENATE FRACTIONS FROM HEADS THAT HAD BEEN INCUBATED: WITH 5 HYDROXYTRYPTAMINE. THE TIME COURSE OF ACCUMULATION OF ENDOGENOUS CAMP CORRELATED HITH ACTIVATION OF PROTEIN: KINESES EXCEPT DURING THE FIRST MINUTE OF INCUBATION HITH 5 HYDROXYTRYPTAMINE. THE DEGREE OF ACTIVATION OF PROTEIN KINASE BY ADDED CAMP WAS INVERSELY CORRELATED WITH ENDOGENOUS CYCLIC NUCLEOTIDEDURING INCUBATION WITH 5 HYDROXYTRYPTAMINE. INCUBATION OF FLUKE HEADS WITH BOTH 5 :HYDROXYTRYPTAMINE'AND D LYSERGIC ACID DIETHYLAMIDE TOGETHER REDUCED THE ACTIVATION OF PROTEIN KINASE BY HYOROXYTRYPTAMINE INCUBATION OF FLUKE HEADS WITH ONLY D LYSERGIC ACID DIETHYLAMIDE HAD NO EFFECT ON PROTEIN' KINASE ACTIVITY. CAMP INCREASED PHOSPHORYLATION OF FLUKE PROTEIN IN BOTH FRACTIONS OF THE HOMOGENATE. THIS PHOSPHORYLATION WAS LESS SENSITIVE TO ACTIYATION BY THE CYCLIC NUCLEOTIDE WHEN THE FLUKE HEADS HAD BEEN INCUBATED WITH 5 HYDROXYTRYPTAMINE. THUS 5 HYDROXYTRYPTAMINE CAN STIMULATE PROTEIN KINASE ACTIVITY TOWARD ENDOGE'NOUS PROTEINS. THE RESULTS INDICATE THAT THE PHYSIOLOGICAL EFFECTS OF 5 HYDROXYTRYPTAMINE ARE MEDIATED BY CAMP ACTIVATION OF PROTEIN KINASE.
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