Myosin light chain kinase phosphorylation in tracheal smooth muscle

Journal Article · Tue Sep 25 00:00:00 EDT 1990 · Journal of Biological Chemistry; (USA)

OSTI ID:6511500

Stull, J T; Hsu, L C; Tansey, M G; Kamm, K E ^[1]

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1. Univ. of Texas Southwestern Medical Center, Dallas (USA)

Purified myosin light chain kinase from smooth muscle is phosphorylated by cyclic AMP-dependent protein kinase, protein kinase C, and the multifunctional calmodulin-dependent protein kinase II. Because phosphorylation in a specific site (site A) by any one of these kinases desensitizes myosin light chain kinase to activation by Ca2+/calmodulin, kinase phosphorylation could play an important role in regulating smooth muscle contractility. This possibility was investigated in {sup 32}P-labeled bovine tracheal smooth muscle. Treatment of tissues with carbachol, KCl, isoproterenol, or phorbol 12,13-dibutyrate increased the extent of kinase phosphorylation. Six primary phosphopeptides (A-F) of myosin light chain kinase were identified. Site A was phosphorylated to an appreciable extent only with carbachol or KCl, agents which contract tracheal smooth muscle. The extent of site A phosphorylation correlated to increases in the concentration of Ca2+/calmodulin required for activation. These results show that cyclic AMP-dependent protein kinase and protein kinase C do not affect smooth muscle contractility by phosphorylating site A in myosin light chain kinase. It is proposed that phosphorylation of myosin light chain kinase in site A in contracting tracheal smooth muscle may play a role in the reported desensitization of contractile elements to activation by Ca2+.

• OSTI ID: 6511500
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 265:27; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL FUNCTIONS
CALCIUM COMPOUNDS
CALMODULIN
CATTLE
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELECTROPHORESIS
ENZYMES
FUNCTIONS
GLOBULINS
HYDROLASES
IN VITRO
ISOTOPES
LIGHT NUCLEI
MAMMALS
MUSCLES
MYOSIN
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
RESPIRATORY SYSTEM
RUMINANTS
SERINE PROTEINASES
TRACHEA
TRANSFERASES
TRYPSIN
TWO-DIMENSIONAL ELECTROPHORESIS
VERTEBRATES