title: β1a490-508, a 19-residue peptide from C-terminal tail of Cav1.1 β1a subunit, potentiates voltage-dependent calcium release in adult skeletal muscle fibers.
abstract: The α1 and β1a subunits of the skeletal muscle calcium channel, Cav1.1, as well as the Ca(2+) release channel, ryanodine receptor (RyR1), are essential for excitation-contraction coupling. RyR1 channel activity is modulated by the β1a subunit and this effect can be mimicked by a peptide (β1a490-524) corresponding to the 35-residue C-terminal tail of the β1a subunit. Protein-protein interaction assays confirmed a high-affinity interaction between the C-terminal tail of the β1a and RyR1. Based on previous results using overlapping peptides tested on isolated RyR1, we hypothesized that a 19-amino-acid residue peptide (β1a490-508) is sufficient to reproduce activating effects of β1a490-524. Here we examined the effects of β1a490-508 on Ca(2+) release and Ca(2+) currents in adult skeletal muscle fibers subjected to voltage-clamp and on RyR1 channel activity after incorporating sarcoplasmic reticulum vesicles into lipid bilayers. β1a490-508 (25 nM) increased the peak Ca(2+) release flux by 49% in muscle fibers. Considerably fewer activating effects were observed using 6.25, 100, and 400 nM of β1a490-508 in fibers. β1a490-508 also increased RyR1 channel activity in bilayers and Cav1.1 currents in fibers. A scrambled form of β1a490-508 peptide was used as negative control and produced negligible effects on Ca(2+) release flux and RyR1 activity. Our results show that the β1a490-508 peptide contains molecular components sufficient to modulate excitation-contraction coupling in adult muscle fibers.
authors: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland.
authors: Erick O
authors: EO
authors: Hernández-Ochoa
authors: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland.
authors: Rotimi O
authors: RO
authors: Olojo
authors: John Curtin School of Medical Research, Australian National University, Canberra, Australia.
authors: Robyn T
authors: RT
authors: Rebbeck
authors: John Curtin School of Medical Research, Australian National University, Canberra, Australia.
authors: Angela F
authors: AF
authors: Dulhunty
authors: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland. Electronic address: mschneid@umaryland.edu.
authors: Martin F
authors: MF
authors: Schneider
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000378:metabolism*; D020013:Calcium Signaling; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism
chemical_list: C529218:CACNA1S protein, mouse; D020746:Calcium Channels, L-Type; D021122:Protein Subunits; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium