Key result
A 14 amino acid motif within the I-II cytoplasmic linker of the alpha1Ca subunit is sufficient to bind beta2a, beta1a, beta3, and beta4 subunits in voltage-gated cardiac L-type calcium channels.
Identified a specific 14 amino acid motif in the I-II cytoplasmic linker of the cardiac L-type calcium channel alpha1Ca subunit that is sufficient for binding beta subunits.
May inform selective L-type channel modulators; leaves open functional validation in mammalian models.
The beta subunits of voltage-gated calcium channels normalize current amplitude, kinetics and voltage dependence of these channels by interacting with the channel's pore forming subunit alpha1. By screening an epitope expression library of alpha1Ca fusion proteins, a beta2a binding site of 22 amino acids was identified within the I-II cytoplasmic linker but not on other cytoplasmic sequences of alpha1Ca. This binding site overlaps by 14 amino acids with the conserved 18 amino acid peptide assumed to be essential for alpha1-beta interaction. The common 14 amino acid motif of alpha1Ca is sufficient to bind beta2a, and in addition beta1a, beta3 and beta4.
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Marquart et al. (1997) studied this question. A 14 amino acid motif within the I-II cytoplasmic linker of the alpha1Ca subunit is sufficient to bind beta2a, beta1a, beta3, and beta4 subunits in voltage-gated cardiac L-type calcium channels.
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