WCH-CD Forms a water-specific channel that provides the plasma membranes of renal collecting duct with high permeability to water, thereby permitting water to move in the direction of an osmotic gradient. Collecting duct water channel protein SIAFSRAVLAEFLATLLFVFFGLGSALNWPQAMPSVLQIAMAFGLAIGTLVQALGHVSGAHINPAVTVACLVGCHVSFLRAAFYVAAQLLGAVAGAALLHEITPPDIRR ADH water channel Aquaporin-CD Water channel protein for renal collecting duct Aquaporin-2 (Fragment) AQP2_HORSE 109 AQP2