Voltage-gated Ca²⁺ (Ca_V) channels are ubiquitously expressed and function as Ca²⁺ conducting pores in the plasma membrane¹. Based on their electrophysiological and pharmacological properties, Ca_V channels have traditionally been classified into L, T, N, P, Q, and R types². L-type Ca²⁺ channels are heteromultimers composed of four independently encoded proteins, the pore-forming α1 subunit, which triggers Ca²⁺ flow across the membrane, and the subunits α2δ, γ, and β³.

 Ca_Vβ subunits play critical roles in membrane trafficking of the channel complex and regulation of voltage-dependent gating. The Ca_Vβ subunit binds to the endoplasmic reticulum (ER) retention signal in the I-II loop of the α1-subunit, which allows channels to traffic to the surface membrane⁴. Furthermore, Ca_Vβ subunits not only allow for membrane trafficking of the channel complex, they also can play a role in determining the subcellular localization of channels on the surface membrane⁵.  There are four distinct Ca_Vβ subunits Ca_Vβ1, Ca_Vβ2, Ca_Vβ3 and Ca_Vβ4⁶.

Three splice variants exist for the β1 subunit: β1a, β1b and β1c. β1a is known to be expressed in skeletal muscle and brain, but not in smooth muscle or heart. β1a appears to be important for the functional expression of the α1 subunit in skeletal muscle⁷. β1b was identified by cloning in rat brain, heart and hippocampus, and differs from β1a by having a deletion of ~50 amino acids at residue 209, and having a 120-residue C-terminal elongation. β1c was cloned from human heart and hippocampus and has the same deletion as β1b, but lacks the C-terminal extension.