Promotes expression of the ion channel CACNA1H at the cell membrane, and thereby contributes to the regulation of channel activity. Plays a minor and redundant role in promoting the expression of calcium channel CACNA1S at the cell membrane, and thereby contributes to increased channel activity. Slows down the inactivation rate of the calcium channel CACNA1C. Interacts (via SH3 domains) with CACNA1S. Interacts with CACNA1H. Interacts with CACNA1C.