Figure 5. Schematic representations of the atoms involved in the postulated ammonia efflux channel in (a) Av protein structure 3U7Q and (b) Kp protein structure 1QH1.

The numbering of O1/O2 and O3/O4 of HCA is reversed in PDB 1QH1, and has been changed to the 3U7Q numbering in this presentation. Water molecules are labeled red; protein atoms are differentiated as chain A yellow and chain B salmon, with main chain atoms boxed and side-chain atoms unboxed; connecting lines are possible hydrogen bonds. The groups coloured green are hydrophobic side-chain components that are potential steric barriers. The aqua enclosures signify the relevant components of the water pool.