Regulatory subunit of the voltage-gated calcium channel that gives rise to L-type calcium currents (PubMed:10684870). Increases CACNA1B peak calcium current and shifts the voltage dependencies of channel activation and inactivation (PubMed:10684870). Increases CACNA1C peak calcium current and shifts the voltage dependencies of channel activation and inactivation (By similarity). Component of a calcium channel complex consisting of a pore-forming alpha subunit (CACNA1C) and the ancillary subunits CACNB3 and CACNA2D1. The channel complex contains alpha, beta, gamma and delta subunits in a 1:1:1:1 ratio. Interacts with CACNA2D4. Interacts with FASLG (By similarity). Interacts with CBARP; prevents the interaction of CACNB3 with the alpha subunit CACNA1C thereby negatively regulating the activity of the corresponding calcium channel (By similarity). Belongs to the calcium channel beta subunit family.