Regulatory subunit of the voltage-gated calcium channel that gives rise to L-type calcium currents (PubMed:8119293). Increases CACNA1B peak calcium current and shifts the voltage dependencies of channel activation and inactivation (By similarity). Increases CACNA1C peak calcium current and shifts the voltage dependencies of channel activation and inactivation (By similarity). {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, ECO:0000269|PubMed:8119293}. This is the function of ENSG00000167535 (CACNB3, calcium voltage-gated channel auxiliary subunit beta 3).