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Cellular and Molecular Life Sciences CMLS

, Volume 58, Issue 2, pp 312–320 | Cite as

Native skeletal muscle dihydropyridine receptor exists as a supramolecular triad complexRID="†"ID="†" Research Article

  • G. R. Froemming
  • K. Ohlendieck*RID="*"ID="*" Corresponding author.

Abstract.

One of the central elements of excitation-contraction coupling, the voltage-sensing dihydropyridine receptor, is believed to exist as a high-molecular-mass complex in the triad junction. Although freeze-fracture electron microscopical analysis suggests a tetrad complex, no direct biochemical evidence exists demonstrating the actual size of the native membrane complex. Using a combination of various two-dimensional gel electrophoresis techniques, we show here that the principal α 1-subunit of the dihydropyridine receptor and its auxiliary α 2-subunit form a triad complex of approximately 2800 kDa under native conditions. Established Ca2+-ATPase tetramers and calsequestrin monomers were employed for the internal standardization of the gel systems used. Thus, the large voltage-sensing complex appears to be tightly associated, since it does not disintegrate during subcellular fractionation and native electrophoresis procedures. Our findings support the cell biological hypothesis that native dihydropyridine receptor units form a tetrad structure within the transverse tubules.

Key words. Dihydropyridine receptor; Ca2+-ATPase; calsequestrin; two-dimensional electrophoresis; triad; skeletal muscle. 

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Copyright information

© Birkhäuser Verlag Basel, 2001

Authors and Affiliations

  • G. R. Froemming
    • 1
  • K. Ohlendieck*RID="*"ID="*" Corresponding author.
    • 1
  1. 1.Department of Pharmacology, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4 (Ireland), Fax +353 1 2692749, e-mail: kay.ohlendieck.ucd.ie IE

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