Abstract
Over 109 molecules/sec of water can pass through aquaporin (AQP). Structure analysis of AQP1 crystal by electron microscopes determined that water molecules pass through and interact with amino acid residues that form the aquaporin pore, and that the hydrogen bond between water molecules are thereby cleaved so that the transfer of protons from outside to inside is interrupted. Another glyceroporin (GLP) has a similar structure to AQP, water can not pass through GLP even though its pore size is lager than that of AQP. We determined the mechanism of passage of both water and glycerol through archaeal aquaglyceroporin, an ancestor of AQP and GLP, by X-ray crystalography. Phylogenetic analyses suggested that the plant GLP (NIP) may have resulted from horizontal gene transfer from bacteria. By studying knock-out bacteria, the AGP of archaea and bacteria appear to be related to growth and the regulation of osmotic balance.
