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Purification and characterization of the mammalian myosin light chain phosphatase holoenzyme. The differential effects of the holoenzyme and its subunits on smooth muscle.

Publication ,  Journal Article
Shirazi, A; Iizuka, K; Fadden, P; Mosse, C; Somlyo, AP; Somlyo, AV; Haystead, TA
Published in: J Biol Chem
December 16, 1994

We have purified to homogeneity from the myofibrillar fraction of pig bladder a mammalian heterotrimeric form of PP-1, SMPP-1M. Purified pig bladder SMPP-1M is similar in composition and substrate specificity to avian gizzard PP-1M reported by Alessi et al. (Alessi, D., Macdougall, L. K., Sola, M. M., Ikebe, M., and Cohen, P. (1992) Eur. J. Biochem. 210, 1023-1035) and consists of the catalytic subunit of PP-1 (37 kDa) and two other equimolar subunits of 130 and 20 kDa. The properties of SMPP-1M and the role of its regulatory subunits in the dephosphorylation of myosin and in the initiation of relaxation were characterized both in vitro and in smooth muscle. We show that the relaxant effect of the catalytic subunit in smooth muscle is markedly potentiated by the addition of the regulatory subunits of SMPP-1M. Our findings demonstrate that SMPP-1M is the major phosphatase dephosphorylating myosin in mammalian smooth muscle and that myosin dephosphorylation is regulated in vivo via targeting subunits that specifically alter the substrate specificity of PP-1C toward myosin.

Duke Scholars

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

December 16, 1994

Volume

269

Issue

50

Start / End Page

31598 / 31606

Location

United States

Related Subject Headings

  • Urinary Bladder
  • Swine
  • Substrate Specificity
  • Phosphorylase Phosphatase
  • Phosphoprotein Phosphatases
  • Peptides, Cyclic
  • Myosins
  • Myosin-Light-Chain Phosphatase
  • Muscle, Smooth
  • Muscle Contraction
 

Citation

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Shirazi, A., Iizuka, K., Fadden, P., Mosse, C., Somlyo, A. P., Somlyo, A. V., & Haystead, T. A. (1994). Purification and characterization of the mammalian myosin light chain phosphatase holoenzyme. The differential effects of the holoenzyme and its subunits on smooth muscle. J Biol Chem, 269(50), 31598–31606.
Shirazi, A., K. Iizuka, P. Fadden, C. Mosse, A. P. Somlyo, A. V. Somlyo, and T. A. Haystead. “Purification and characterization of the mammalian myosin light chain phosphatase holoenzyme. The differential effects of the holoenzyme and its subunits on smooth muscle.J Biol Chem 269, no. 50 (December 16, 1994): 31598–606.
Shirazi A, Iizuka K, Fadden P, Mosse C, Somlyo AP, Somlyo AV, et al. Purification and characterization of the mammalian myosin light chain phosphatase holoenzyme. The differential effects of the holoenzyme and its subunits on smooth muscle. J Biol Chem. 1994 Dec 16;269(50):31598–606.
Shirazi A, Iizuka K, Fadden P, Mosse C, Somlyo AP, Somlyo AV, Haystead TA. Purification and characterization of the mammalian myosin light chain phosphatase holoenzyme. The differential effects of the holoenzyme and its subunits on smooth muscle. J Biol Chem. 1994 Dec 16;269(50):31598–31606.

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

December 16, 1994

Volume

269

Issue

50

Start / End Page

31598 / 31606

Location

United States

Related Subject Headings

  • Urinary Bladder
  • Swine
  • Substrate Specificity
  • Phosphorylase Phosphatase
  • Phosphoprotein Phosphatases
  • Peptides, Cyclic
  • Myosins
  • Myosin-Light-Chain Phosphatase
  • Muscle, Smooth
  • Muscle Contraction