Myosin light chain phosphorylation in sup 32 P-labeled rabbit aorta stimulated by phorbol 12,13-dibutyrate and phenylephrine

Journal Article · Fri Dec 15 00:00:00 EST 1989 · Journal of Biological Chemistry; (USA)

OSTI ID:5029510

Singer, H A; Oren, J W; Benscoter, H A ^[1]

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1. Sigfried and Janet Weis Center for Research, Danville, PA (USA)

The mechanism(s) of force development in vascular smooth muscle following pharmacological activation of protein kinase C by phorbol esters are not known. In this study, we examined the myosin light chain phosphorylation response following stimulation by phorbol 12,13-dibutyrate (PDB) or phenylephrine in rabbit aorta which had been incubated with 32PO4 in order to label ATP pools. Through tryptic phosphopeptide mapping of myosin light chain from intact tissue and comparison to controls using purified components, we inferred that Ca2+-dependent force stimulated by PDB was associated with small increases in serine-19 phosphorylation, consistent with a contractile mechanism involving indirect activation of myosin light chain kinase. Additional residues, consistent with the in vitro substrate specificity of protein kinase C, were also observed to be phosphorylated in response to PDB and represented proportionately a larger fraction of the total phosphorylated myosin light chain in Ca2+-depleted tissues. Stimulation by an alpha 1-adrenergic agonist (phenylephrine) resulted in phosphorylation of residues which were consistent with an activation mechanism involving myosin light chain kinase only. These results indicate that in rabbit aorta the contractile effects of PDB may be partially mediated by Ca2+-dependent activation of myosin light chain kinase. However, the data do not rule out a component of the PDB-stimulated contractile response which is independent of myosin light chain phosphorylation on the serine-19 residue. In addition, activation by a more physiological stimulus, phenylephrine, does not result in protein kinase C-mediated myosin light chain phosphorylation.

• OSTI ID: 5029510
• Journal Information: Journal of Biological Chemistry; (USA), Vol. 264:35; ISSN 0021-9258
• Country of Publication: United States
• Language: English

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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
MYOSIN
PHOSPHORYLATION
PHORBOL ESTERS
BIOLOGICAL EFFECTS
PHOSPHOTRANSFERASES
ENZYME ACTIVITY
AMINO ACIDS
AORTA
BIOCHEMICAL REACTION KINETICS
ELECTROPHORESIS
IN VITRO
MUSCLES
PEPTIDES
PHOSPHORUS 32
RABBITS
TRACER TECHNIQUES
TRYPSIN
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARBOXYLIC ACIDS
CARCINOGENS
CARDIOVASCULAR SYSTEM
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ENZYMES
ESTERS
GLOBULINS
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HYDROLASES
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
SERINE PROTEINASES
TRANSFERASES
VERTEBRATES
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