Plant anion channel protein homologue, molecular model. Obtained from the bacterium Haemophilus influenzae, this anion channel protein (TehA) is being studied due to its common structure (homologue) with the plant slow anion channel protein SLAC1. The SLAC1 anion channel controls turgor pressure in the guard cells of plant stomata, thus playing a key role in the exchange of water and gases between the plant and the external environment. SLAC1 is a symmetrical trimer that forms a central five-helix transmembrane pore.