Genetic characterization of a new splice variant of the beta2 subunit of the voltage-dependent calcium channel.

This study reports a novel splice variant form of the voltage-dependent calcium channel beta2 subunit (beta2g). This variant is composed of the conserved amino-terminal sequences of the beta2a subunit, but lacks the beta-subunit interaction domain (BID), which is thought essential for interactions with the alpha1 subunit. Gene structure analysis revealed that this gene was composed of 13 translated exons spread over 107 kb of the genome. The gene structure of the beta2 subunit was similar in exon-intron organization to the murine beta3 and human beta4 subunits. Electrophysiological evaluation revealed that beta2a and 2g affected channel properties in different ways. The beta2a subunit increased the peak amplitude, but failed to increase channel inactivation, while beta2g had no significant effects on either the peak current amplitude or channel inactivation. Other beta3 subunits, such as beta3 and beta4, significantly increased the peak current and accelerated current inactivation.