Molecular Partners of Voltage-Gated Calcium Channel β and α2δ Auxiliary Subunits: Roles in Channel Complex Regulation and Beyond

Abstract Research on the auxiliary subunits β (Ca V β) and α 2 δ (Ca V α 2 δ) of voltage-gated calcium channels has gained increasing interest as novel and unexpected functional interactions for these proteins are discovered. Beyond their classic role as regulators of the channel complex, these subunits participate in the spatiotemporal fine-tuning of the channels and in diverse cellular processes. Currently, multiple studies are investigating the interactions between Ca V β and Ca V α 2 δ with other proteins outside the channel complex, and how these associations affect relevant cellular functions such as cell growth, differentiation, and gene expression beyond their effects on channel activity. The auxiliary subunits have also been observed to associate with components involved in calcium channel biogenesis, a process independent of the direct modulation of channel activity. Furthermore, their involvement in the intracellular transport of other channels and receptors, as well as in nuclear signaling, has been demonstrated. The expression of different variants or isoforms may fulfill specific functions in diverse tissues and developmental stages, even outside the channel complex. Undoubtedly, the study of these proteins as scaffolding or regulatory molecules for other proteins has significantly enriched our understanding of their influence on cell signaling and excitability. Graphical Abstract