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), Vol. 265:27; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

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