第293回 平成22年12月3日
(第179回 遺伝子機能解析分野セミナー)

演題 Unexpected Diversities in Plant Aquaporins
   Azad Md. Abul Kalam(Shahjalal University of Science and Technology)
 
 Aquaporins (AQPs) are channel-forming proteins that are integrated into the cellular membranes, and are found in all living organisms. AQPs have been reported recently to be transporters not only of water but also of other substrates of physiological significance. Immense diversities in structures, functions, regulations and physiological roles of plant AQPs are currently observed in model plants, which might be more divergent in other higher plants. Following characterization of four plasma membrane AQPs, we propose that the reversible phosphorylation of a putative homologue is involved in the regulation of temperature-dependent and water transport-associated tulip petal opening and closing movements. Two tonoplast AQPs have been characterized with water channel activity, which might play a role in maintaining osmotic equilibrium during tulip petal movement. Both tonoplast AQPs have a novel Ile in the aromatic/arginine (ar/R) selectivity filter; the residue at the corresponding position is Val or Arg in all AQPs in model plants. Our studies suggest that the amino acid at this position in the ar/R filter is a critical determinant of the transport selectivity profiles and transport rate of AQPs, and further, tonoplast AQPs might have contributions to petal development.