The L-type calcium channel in the heart: the beat goes on
J. Clin. Invest. Ilona Bodi, et al. 115:3306 doi:10.1172/JCI27167 [Go to this article.]

Figure 2
Structural organization of L-VDCCs. The predicted membrane topological organization of the core subunits, their interactions, and structural domains of the auxiliary subunits, which are common to all VDCC types, are shown. The primary structure of the pore-forming α₁ subunit is composed of 4 homologous repeating motifs (I–IV), each of which consists of 6 putative transmembrane segments (S1–S6). The cytoplasmic loops are named according to the motifs they link. The α₂δ and γ (not shown in the Figure) subunits contain transmembrane domains whereas the β subunit is entirely intracellular. Sites of interaction between subunits are indicated. The numbers point to areas found to be important for specific channel functions. The EF hand, A, C, and IQ motifs represent specific peptide sequences involved in CaM binding. Key amino acids required for Ca²⁺ antagonist binding are represented in red letters. At least 5 consensus sites for phosphorylation by cAMP-dependent PKA have been discovered within the C terminal tail of α_1C. AKAP79 (79 kDa A-kinase–anchoring protein) helps to target PKA to its specific substrate. COOH, carboxyterminal.