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Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin. Synergism with cyclic nucleotide-activated kinase.

Publication ,  Journal Article
Wu, X; Haystead, TA; Nakamoto, RK; Somlyo, AV; Somlyo, AP
Published in: J Biol Chem
May 1, 1998

Incorporation of 32P into telokin, a smooth muscle-specific, 17-18-kDa, acidic (pI 4.2-4.4) protein, was increased by forskolin (20 microM) in intact rabbit ileum smooth muscle (ileum) and by 8-bromo-cyclic GMP (100 microM) in alpha-toxin-permeabilized ileum. Native telokin (5-20 microM), purified from turkey gizzard, and recombinant rabbit telokin, expressed in Escherichia coli and purified to >90% purity, induced dose-dependent relaxation, associated with a significant decrease in regulatory myosin light chain phosphorylation, without affecting the rate of thiophosphorylation of regulatory myosin light chain of ileum permeabilized with 0.1% Triton X-100. Endogenous telokin was lost from ileum during prolonged permeabilization (>20 min) with 0.1% Triton X-100, and the time course of loss was correlated with the loss of 8-bromo-cyclic GMP-induced calcium desensitization. Recombinant and native gizzard telokins were phosphorylated, in vitro, by the catalytic subunit of cAMP-dependent protein kinase, cGMP-dependent protein kinase, and p42/44 mitogen-activated protein kinase; the recombinant protein was also phosphorylated by calmodulin-dependent protein kinase II. Exogenous cGMP-dependent protein kinase (0.5 microM) activated by 8-bromo-cyclic GMP (50 microM) phosphorylated recombinant telokin (10 microM) when added concurrently to ileum depleted of its endogenous telokin, and their relaxant effects were mutually potentiated. Forskolin (20 microM) also increased phosphorylation of telokin in intact ileum. We conclude that telokin induces calcium desensitization in smooth muscle by enhancing myosin light chain phosphatase activity, and cGMP- and/or cAMP-dependent phosphorylation of telokin up-regulates its relaxant effect.

Duke Scholars

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

May 1, 1998

Volume

273

Issue

18

Start / End Page

11362 / 11369

Location

United States

Related Subject Headings

  • Sulfhydryl Compounds
  • Recombinant Proteins
  • Rabbits
  • Phosphorylation
  • Peptides
  • Peptide Fragments
  • Myosin-Light-Chain Kinase
  • Muscle, Smooth
  • Muscle Relaxation
  • Muscle Proteins
 

Citation

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Wu, X., Haystead, T. A., Nakamoto, R. K., Somlyo, A. V., & Somlyo, A. P. (1998). Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin. Synergism with cyclic nucleotide-activated kinase. J Biol Chem, 273(18), 11362–11369. https://doi.org/10.1074/jbc.273.18.11362
Wu, X., T. A. Haystead, R. K. Nakamoto, A. V. Somlyo, and A. P. Somlyo. “Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin. Synergism with cyclic nucleotide-activated kinase.J Biol Chem 273, no. 18 (May 1, 1998): 11362–69. https://doi.org/10.1074/jbc.273.18.11362.
Wu, X., et al. “Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin. Synergism with cyclic nucleotide-activated kinase.J Biol Chem, vol. 273, no. 18, May 1998, pp. 11362–69. Pubmed, doi:10.1074/jbc.273.18.11362.
Wu X, Haystead TA, Nakamoto RK, Somlyo AV, Somlyo AP. Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin. Synergism with cyclic nucleotide-activated kinase. J Biol Chem. 1998 May 1;273(18):11362–11369.

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

May 1, 1998

Volume

273

Issue

18

Start / End Page

11362 / 11369

Location

United States

Related Subject Headings

  • Sulfhydryl Compounds
  • Recombinant Proteins
  • Rabbits
  • Phosphorylation
  • Peptides
  • Peptide Fragments
  • Myosin-Light-Chain Kinase
  • Muscle, Smooth
  • Muscle Relaxation
  • Muscle Proteins