These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Regulation of expressed truncated smooth muscle myosins. Role of the essential light chain and tail length.
    Author: Trybus KM.
    Journal: J Biol Chem; 1994 Aug 19; 269(33):20819-22. PubMed ID: 8063695.
    Abstract:
    Regulatory light chain (RLC) phosphorylation controls smooth muscle myosin's ability to act as a molecular motor. If thick filament-regulated myosins share a common structural basis for the "on-off" switch, then the interface between the RLC and essential light chain (ELC) should be as important in smooth muscle myosin as it is for calcium-dependent regulation in molluscan myosin (Xie, X., Harrison, D. H., Schlichting, I., Sweet, R. M., Kalabokis, V. N., Szent-Györgyi, A. G., and Cohen, C. (1994) Nature 368, 306-312). To test this hypothesis, a baculovirus expression system was used to obtain a truncated smooth muscle myosin that contained its native RLC and either smooth ELC, skeletal ELC, or no ELC. Movement of actin in a motility assay by heavy meromyosin (HMM) containing either skeletal or smooth ELC occurred at the same rate and in a phosphorylation-dependent manner. In contrast, substitution of skeletal RLC for smooth RLC produced an inactive molecule. HMM without an ELC moved actin at 25% the rate of control HMM, but the movement was phosphorylation-dependent even without an RLC/ELC interface. Poor regulation was observed, however, when the tail was truncated from 72 to 27 nm even though this species was primarily double-headed. These results suggest that the molecular changes induced at the active site by phosphorylation can occur independent of the ELC, but critically depend upon a stable coiled-coil tail that determines how the RLCs interact at the head/rod junction.
    [Abstract] [Full Text] [Related] [New Search]