Genetic characterization of a new splice variant of the β₂ subunit of the voltage-dependent calcium channel

This study reports a novel splice variant form of the voltage-dependent calcium channel β₂ subunit (β_2g): This variant is composed of the conserved amino-terminal sequences of the β_2a subunit, but lacks the β-subunit interaction domain (BID), which is thought essential for interactions with the α₁ 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 β₂ subunit was similar in exon-intron organization to the murine β₃ and human β₄ subunits. Electrophysiological evaluation revealed that β_2a and β_2g, affected channel properties in different ways. The β_2a subunit increased the peak amplitude, but failed to increase channel inactivation, while β_2g had no significant effects on either the peak current amplitude or channel inactivation. Other β subunits, such as β₃ and β₄, significantly increased the peak current and accelerated current inactivation.