1.A.8.13.5
Aquaporin, Aqp9, of 231 aas and 6 TMSs.  This protein co-localizes with the vacuolar proton pyrophosphatase to acidocalcisomes and the contractile vacuole complex (Montalvetti et al. 2004) which are involved in osmoregulation (Rohloff et al. 2004). Acidocalcisomes function as storage sites for cations and phosphorus, participate in PPi and poly P metabolism as well as volume regulation and are essential for virulence. A signalling pathway involving cyclic AMP generation is important for fusion of acidocalcisomes to the contractile vacuole complex, transference of aquaporin and volume regulation (Docampo et al. 2011). Hyperosmotic stress induces aquaporin-dependent cell shrinkage, polyphosphate synthesis, amino acid accumulation, and global gene expression changes in Trypanosoma cruzi (Li et al. 2011). Plasmodium spp. express a single AQP, Toxoplasma gondii two, while Trypanosoma cruzi and Leishamnia spp. encode up to five AQPs. Their AQPs are thought to import metabolic precursors and simultaneously to dispose of waste and to help parasites survive osmotic stress (Von Bülow and Beitz 2015).