Evaluation of myosin light chain phosphorylation in isolated pancreatic acini

Journal Article · Fri Jan 01 04:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:7027141

Burnham, D B; Soeling, H D; Williams, J A ^[1]

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1. Univ. of California, San Francisco (USA) Universitaet Goettingen (West Germany)

The role of contractile proteins in secretory granule exocytosis was evaluated by determining whether myosin light chain phosphorylation was altered during stimulation of secretion in mouse pancreatic acini. Acinar myosin was purified by extraction into isosmotic sucrose solution containing 40 mM pyrophosphate followed by ammonium sulfate precipitation and Sepharose 4B-CL chromatography. Myosin was eluted as a single peak of K{sup +}-EDTA ATPase activity and was purified over 2,000-fold to a final ATPase specific activity of 0.96 {mu}mol{center dot}min{sup {minus}1}{center dot}mg protein {sup {minus}1}. Three major myosin subunits of apparent M{sub r} of 200,000, 20,000, and 17,000 were present in the purified myosin preparation. A fourth protein of M{sub r} 21,000 was also present. Purification of myosin from {sup 32}P-labeled acini revealed that M{sub r} 200,000, 21,000, and 20,000 proteins to be heavily labeled. The effect of cholecystokinin octapeptide (CCK-8) on myosin phosphorylation was studied after isolation of myosin from {sup 32}P-labeled acinar lysates by immunoprecipitation. Treatment of acini for 1-10 min with a concentration of CCK-8 that gives a maximal secretory response caused a 25-40% increase in light chain labeling. Treatment with a supramaximal CCK-8 concentration produced a 50-80% increase in light chain labeling. Phosphorylation of myosin heavy chain was not significantly affected by secretagogue treatment. These results indicate that stimulation of pancreatic acinar secretion is accompanied by an increase in myosin light chain phosphorylation.

• OSTI ID: 7027141
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 254:1; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BODY
CHEMICAL REACTIONS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ENDOCRINE GLANDS
GLANDS
GLOBULINS
ISOTOPES
KININS
LIGHT NUCLEI
MAMMALS
MICE
MYOSIN
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PANCREAS
PEPTIDES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORYLATION
POLYPEPTIDES
PROTEINS
RADIOISOTOPES
RODENTS
SECRETION
VERTEBRATES