The Ca2+ channel beta4c subunit interacts with heterochromatin protein 1 via a PXVXL binding motif.

The β subunits of voltage-gated Ca(2+) channels are best known for their roles in regulating surface expression and gating of voltage-gated Ca(2+) channel α(1) subunits. Recent evidence, however, indicates that these proteins have a variety of Ca(2+) channel-independent functions. For example, on the molecular level, they regulate gene expression, and on the whole animal level, they regulate early cell movements in zebrafish development.

Alternative splicing of the voltage-gated Ca2+ channel beta4 subunit creates a uniquely folded N-terminal protein binding domain with cell-specific expression in the cerebellar cortex.

Ca2+ channel beta subunits regulate cell-surface expression and gating of voltage-dependent Ca2+ channel alpha1 subunits. Based on primary sequence comparisons, beta subunits are predicted to be modular structures composed of five domains (A-E) that are related to the large family of membrane-associated guanylate kinase proteins. The crystal structure of the beta subunit core B-D domains has been reported recently; however, little is known about the structures of the A and E domains.