The Journal of Membrane Biology

, Volume 179, Issue 2, pp 127–141

Characterization of the Ryanodine Receptor-Ca2+ Release Channel from the Thoracic Tissues of the Lepidopteran Insect Heliothis virescens

  • T.S.  Scott-Ward
  • S.J.  Dunbar
  • J.D.  Windass
  • A.J.  Williams

DOI: 10.1007/s002320010043

Cite this article as:
Scott-Ward, T., Dunbar, S., Windass, J. et al. J. Membrane Biol. (2001) 179: 127. doi:10.1007/s002320010043

Abstract.

The existence of invertebrate forms of the RyR has recently been confirmed (Takeshima et al., 1994, Puente et al., 2000). However, information on the functional properties of this insect RyR is still limited. We report the functional characterization of a RyR from the thoracic muscle of H. virescens (Scott-Ward et al., 1997). A simple purification protocol produced membranes from homogenized prefrozen H. virescens thoracic muscle with a [3H]-ryanodine binding activity of 1.19 ± 0.21 pmol/mg protein (mean ±se; n= 4). [3H]-Ryanodine binding to the H. virescens receptor was dependent on the ryanodine concentration in a hyperbolic fashion with a KD of 3.82 nm (n= 4). [3H]-ryanodine binding was dependent on [Ca2+] in a biphasic manner and was stimulated by 1 mm ATP. Millimolar caffeine did not stimulate [3H]-ryanodine binding to H. virescens membranes in the presence of either nanomolar or micromolar Ca2+. A protein of at least 400 KDa was recognized in H. virescens membrane proteins by a specific anti-H. virescens RyR antibody. Discontinuous density sucrose gradient fractionation of microsomal membranes produced vesicles suitable for single-channel studies. Ca2+-sensitive, Ca2+-permeable channels were successfully inserted into artificial lipid bilayers from H. virescens membrane vesicles. The H. virescens RyR-channel displayed a Ca2+ conductance of ∼110 pS and underwent a persistent and characteristic modification of ion handling and gating following addition of 100 nm ryanodine. The gating of H. virescens channels was sensitive to ATP and ruthenium red in a manner similar to mammalian RyR. This is the first report to describe the single channel and [3H]-ryanodine binding properties of a native insect RyR.

Key words: Insect — Ryanodine — Ryanodine receptor — Calcium channel — Sarcoplasmic reticulum

Copyright information

© 2001 Springer-Verlag New York Inc.

Authors and Affiliations

  • T.S.  Scott-Ward
    • 1
  • S.J.  Dunbar
    • 2
  • J.D.  Windass
    • 2
  • A.J.  Williams
    • 1
  1. 1.Cardiac Medicine, National Heart & Lung Institute, Imperial College School of Medicine, Dovehouse Street, London, UK SW3 6LYGB
  2. 2.Zeneca Agrochemicals, Jealotts Hill, Bracknell, Berkshire, UK RG42 6ETGB