Figure 1

The structures of AQP monomer and homotetramers. (A) Each AQP monomer has six titled α-helical domains to form a water pore spanning plasma membrane. Conserved sequence motifs NPA on the loops bend into molecule to pair with each other and form the water channel. C, in red, represents a cysteine residue (Cys 189) that can block the AQPs function with functional sensitivity to mercury. (B) The structure of AQP homotetramers from side view. Each AQP monomer contains independently a water pore. AQP monomers assemble as homotetramers to form a central pore in homotetramers. Red arrow represents the central pore with transporting gas and ions. Blue arrow represents the water pore with transporting water and solutes. (C) The structure of AQP homotetramers from the top view. Each AQP monomer contains independently a water pore. AQP monomers assemble as homotetramers to form a central pore in homotetramers.