This competition between channels is supported by VGCC overexpression experiments in mammalian neurons that demonstrate overexpression of PQ channels with channelopathy mutations compete with wildtype channels for AZ localization, and that overexpressing the Cav2 α1 subunit fails to increase Cav2 levels at AZs (Cao et al., 2004; Cao and Tsien, 2010; Hoppa et al., 2012). The gene discussed is CAV2; the disease is channelopathy.