Figure 2. Domains in β and α₂δ subunits and their interaction with the α₁ subunit .

A, topology of the calcium channel complex. B, known domains in β subunits. C, known domains in α₂δ subunits. D, approximate phylogenetic tree generated for mouse α₂δ subunits using http://www.phylogeny.fr/. The VWA and Cache containing protein Cachd1 is included for comparison. The sequences AAI15872.1, AAH56389.1, EDL24740.1, AAI41092.1 and NP_932154.1 were used.