Referenced in: none

Automatically associated channels: Cav2.1 , Slo1

Title: Molecular characterization of a two-domain form of the neuronal voltage-gated P/Q-type calcium channel alpha(1)2.1 subunit.

Authors: Jyothi Arikkath, Ricardo Felix, Christopher Ahern, Chien-Chang Chen, Yasuo Mori, Inseon Song, Hee-Sup Shin, Roberto Coronado, Kevin P Campbell

Journal, date & volume: FEBS Lett., 2002 Dec 18 , 532, 300-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/12482583

Abstract
We characterized the neuronal two-domain (95kD-alpha(1)2.1) form of the alpha(1)2.1 subunit of the voltage-gated calcium channels using genetic and molecular analysis. The 95kD-alpha(1)2.1 is absent in neuronal preparations from CACNA1A null mouse demonstrating that alpha(1)2.1 and 95kD-alpha(1)2.1 arise from the same gene. A recombinant two-domain form (alpha(1AI-II)) of alpha(1)2.1 associates with the beta subunit and is trafficked to the plasma membrane. Translocation of the alpha(1AI-II) to the plasma membrane requires association with the beta subunit, since a mutation in the alpha(1AI-II) that inhibits beta subunit association reduces membrane trafficking. Though the alpha(1AI-II) protein does not conduct any voltage-gated currents, we have previously shown that it generates a high density of non-linear charge movements [Ahern et al., Proc. Natl. Acad. Sci. USA 98 (2001) 6935-6940]. In this study, we demonstrate that co-expression of the alpha(1AI-II) significantly reduces the current amplitude of alpha(1)2.1/beta(1a)/alpha(2)delta channels, via competition for the beta subunit. Taken together, our results demonstrate a dual functional role for the alpha(1AI-II) protein, both as a voltage sensor and modulator of P/Q-type currents in recombinant systems. These studies suggest an in vivo role for the 95kD-alpha(1)2.1 in altering synaptic activity via protein-protein interactions and/or regulation of P/Q-type currents.