The β1a subunit of the skeletal DHPR binds to skeletal RyR1 and activates the channel via its 35-residue C-terminal tail

Robyn T. Rebbeck, Yamuna Karunasekara, Esther M. Gallant, Philip G. Board, Nicole A. Beard, Marco G. Casarotto, Angela F. Dulhunty

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28 Scopus citations

Abstract

Although it has been suggested that the C-terminal tail of the β1a subunit of the skeletal dihyropyridine receptor (DHPR) may contribute to voltage-activated Ca2+ release in skeletal muscle by interacting with the skeletal ryanodine receptor (RyR1), a direct functional interaction between the two proteins has not been demonstrated previously. Such an interaction is reported here. A peptide with the sequence of the C-terminal 35 residues of β1a bound to RyR1 in affinity chromatography. The full-length β1a subunit and the C-terminal peptide increased [3H]ryanodine binding and RyR1 channel activity with an AC 50 of 450-600 pM under optimal conditions. The effect of the peptide was dependent on cytoplasmic Ca2+, ATP, and Mg2+ concentrations. There was no effect of the peptide when channel activity was very low as a result of Mg2+ inhibition or addition of 100 nM Ca 2+ (without ATP). Maximum increases were seen with 1-10 mM Ca 2+, in the absence of Mg2+ inhibition. A control peptide with the C-terminal 35 residues in a scrambled sequence did not bind to RyR1 or alter [3H]ryanodine binding or channel activity. This high-affinity in vitro functional interaction between the C-terminal 35 residues of the DHPR β1a subunit and RyR1 may support an in vivo function of β1a during voltage-activated Ca2+ release.

Original languageEnglish (US)
Pages (from-to)922-930
Number of pages9
JournalBiophysical journal
Volume100
Issue number4
DOIs
StatePublished - Feb 16 2011

Bibliographical note

Funding Information:
This work was supported by the National Health and Medical Research Council (471462 to A.F.D., M.G.C., and P.G.B.).

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