1.A.14.2.3
The 7 TMS proton-sensitive Ca²⁺ leak channel, YetJ.  The activity and high resolution 3-d structure have been determined (Chang et al. 2014). BsYetJ in lipid nanodiscs is structurally different from those crystallized in detergents. Li et al. 2020 showed that the BsYetJ conformation is pH-sensitive in the apo state (lacking calcium), whereas in a calcium-containing solution it is stuck in an intermediate state, inert to pH changes. Only when the transmembrane calcium gradient is established can the calcium-release activity of holo-BsYetJ occur and be mediated by pH-dependent conformational changes, suggesting a dual gating mechanism. Conformational substates involved in the process and a key residue, D171, relevant to the gating of calcium were identified. Thus, BsYetJ/TMBIM6 is a pH-dependent, voltage-gated calcium channel (Li et al. 2020).