Regulation of cardiac C-protein phosphorylation
Molecular mechanisms of cardiac sympathetic and parasympathetic responses were addressed by studying subcellular changes in protein phosphorylation, cAMP-dependent protein kinase activity and protein phosphatase activity in frog hearts. B-adrenergic agonists increased and muscarinic cholinergic agonists decreased (/sup 32/P)phosphate incorporation into C-protein, a thick filament component. Regulation of protein phosphatase activity by Iso and methacholine (MCh) was assayed using extracts of drug treated frog hearts and (/sup 32/P)phospho-C-protein as substrate. Total phosphatase activity decreased 21% in extracts from hearts perfused with 0.1 ..mu..M Iso and 17% in hearts exposed to Iso plus 1 ..mu..M methacholine. This decrease reflected decreased phosphatase-2A activity. No changes in total phosphatase activity were measurable in broken cells treated with Iso or MCh. The results suggest adrenergic stimulation changes contractile activity in frog hearts by activating cAMP-dependent protein kinase associated with particulate cellular elements and inactivating soluble protein phosphatase-2A. This is the first demonstration of coordinated regulation of these enzymes by B-adrenergic agonists favoring phosphorylation of effector proteins. Coordinated regulation by methacholine in the presence of Iso was not observed.
- Research Organization:
- Emory Univ., Atlanta, GA (USA)
- OSTI ID:
- 6710064
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PROTEINS
PHOSPHORYLATION
AUTONOMIC NERVOUS SYSTEM
FROGS
HEART
LABELLED COMPOUNDS
PHOSPHORUS 32
PHOSPHOTRANSFERASES
SYMPATHOMIMETICS
TRACER TECHNIQUES
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARDIOVASCULAR SYSTEM
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DRUGS
ENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NERVOUS SYSTEM
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
RADIOISOTOPES
TRANSFERASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques