Myosin light chain kinase phosphorylation in tracheal smooth muscle

• Published in: The Journal of biological chemistry 1990-09, Vol.265 (27), p.16683-16690
• Main Authors: Stull, J T, Hsu, L C, Tansey, M G, Kamm, K E
• Format: Article
• Language: English
• Subjects: 550201 - Biochemistry- Tracer Techniques; ALKALINE EARTH METAL COMPOUNDS; Analytical, structural and metabolic biochemistry; ANIMALS; AUTORADIOGRAPHY; BASIC BIOLOGICAL SCIENCES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; Biological and medical sciences; BIOLOGICAL FUNCTIONS; CALCIUM COMPOUNDS; CALMODULIN; Carbachol - pharmacology; CATTLE; CHEMICAL REACTIONS; DAYS LIVING RADIOISOTOPES; DOMESTIC ANIMALS; ELECTROPHORESIS; Electrophoresis, Gel, Two-Dimensional; ENZYMES; Enzymes and enzyme inhibitors; FUNCTIONS; Fundamental and applied biological sciences. Psychology; GLOBULINS; HYDROLASES; IN VITRO; In Vitro Techniques; Isometric Contraction - drug effects; Isoproterenol - pharmacology; ISOTOPES; Kinetics; LIGHT NUCLEI; MAMMALS; Muscle, Smooth - drug effects; Muscle, Smooth - enzymology; Muscle, Smooth - physiology; MUSCLES; MYOSIN; myosin light chain kinase; Myosin-Light-Chain Kinase - metabolism; NUCLEI; ODD-ODD NUCLEI; ORGANIC COMPOUNDS; PEPTIDE HYDROLASES; Phorbol 12,13-Dibutyrate - pharmacology; Phosphopeptides - isolation & purification; PHOSPHORUS 32; PHOSPHORUS ISOTOPES; Phosphorus Radioisotopes; PHOSPHORUS-GROUP TRANSFERASES; PHOSPHORYLATION; PHOSPHOTRANSFERASES; Potassium Chloride - pharmacology; protein kinase; Protein Kinase C - metabolism; PROTEINS; RADIOISOTOPES; RESPIRATORY SYSTEM; RUMINANTS; SERINE PROTEINASES; smooth muscle; TRACHEA; Trachea - drug effects; Trachea - enzymology; Trachea - physiology; TRANSFERASES; TRYPSIN; TWO-DIMENSIONAL ELECTROPHORESIS; VERTEBRATES
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)46275-2

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 32P-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+.