Cx26CT domain is involved in inhibition by taurine. The protonated amine of the AS is involved in connexin binding, and the ionized sulfonate moiety is involved in effecting the inhibition (Tao and Harris, 2004). (A) Side view of taurine showing the energy-minimized conformation determined using the MMFF94 force field rule. Black, carbon; red, oxygen; gray, nitrogen; blue, sulfur. (Below) Its molecular orbital structure (0.002 Å3/atomic unit; transparency) determined by Hartree–Fock 6–31G* ab initio models, subject to MMFF94 equilibrium geometry constraints; electrostatic potential (red, negative; blue, positive) and local ionization potential (red, ionized; blue, nucleophile) were mapped onto this orbital surface. (B) Energy-minimized conformations, in scale with A, of wild-type (nontagged) Cx26CT (left) and Cx26Tc CT (right), as determined using the MMFF94 force field rule. Note two surface side-facing acidic lysine residues (K231 and K233), which may interact with the sulfonate group of taurine and/or be involved in pore occlusion.
