Aquaporin-8 (AQP-8)
1_MSGEI 6_ AMCEP 11_ EFGND 16_ KAREP 21_ SVGGR 26_ WRVSW 31_ YERFV 36_ QPCLV 41_ ELLGS 46_ ALFIF 51_ IGCLS 56_ VIENG 61_ TDTGL 66_ LQPAL 71_ AHGLA 76_ LGLVI 81_ ATLGN 86_ ISGGH 91_ FNPAV 96_ SLAAM 101_ LIGGL 106_ NLVML 111_ LPYWV 116_ SQLLG 121_ GMLGA 126_ ALAKA 131_ VSPEE 136_ RFWNA 141_ SGAAF 146_ VTVQE 151_ QGQVA 156_ GALVA 161_ EIILT 166_ TLLAL 171_ AVCMG 176_ AINEK 181_ TKGPL 186_ APFSI 191_ GFAVT 196_ VDILA 201_ GGPVS 206_ GGCMN 211_ PARAF 216_ GPAVV 221_ ANHWN 226_ FHWIY 231_ WLGPL 236_ LAGLL 241_ VGLLI 246_ RCFIG 251_ DGKTR 256_LILKA
1: Channel that allows the facilitated permeation of water and uncharged molecules, such as hydrogen peroxide and the neutral form of ammonia (NH3), through cellular membranes such as plasma membrane, inner mitochondrial membrane and endoplasmic reticulum membrane of several tissues (PubMed:15948717, PubMed:18948439, PubMed:23541115, PubMed:26972385, PubMed:29732408, PubMed:30579780). The transport of the ammonia neutral form induces a parallel transport of proton, at alkaline pH when the concentration of ammonia is high (By similarity). However, it is unclear whether the transport of proton takes place via the aquaporin or via an endogenous pathway (By similarity). Also, may transport ammonia analogs such as formamide and methylamine, a transport favourited at basic pH due to the increase of unprotonated (neutral) form, which is expected to favor diffusion (PubMed:15948717). Does not transport urea or glycerol (PubMed:15948717). The water transport mechanism is mercury- and copper-sensitive and passive in response to osmotic driving forces (PubMed:15948717). At the canicular plasma membrane, mediates the osmotic transport of water toward the bile canaliculus and facilitates the cAMP-induced bile canalicular water secretion, a process involved in bile formation (PubMed:18948439). In addition, mediates the hydrogen peroxide release from hepatocyte mitochondria that modulates the SREBF2-mediated cholesterol synthesis and facilitates the mitochondrial ammonia uptake which is metabolized into urea, mainly under glucagon stimulation (PubMed:30579780, PubMed:34292591). In B cells, transports the CYBB-generated hydrogen peroxide from the external leaflet of the plasma membrane to the cytosol to promote B cell activation and differentiation for signal amplification (By similarity). In the small intestine and colon system, mediates water transport through mitochondria and apical membrane of epithelial cells (By similarity). May play an important role in the adaptive response of proximal tubule cells to acidosis possibly by facilitating the mitochondrial ammonia transport (PubMed:22622463)