The aquaporins (AQPs) are a family of integral membrane proteins composed of two subfamilies: the orthodox aquaporins, which transport only water, and the aquaglyceroporins, which transport glycerol, urea, or other small solutes []. AQP1 in pleural mesothelial cells participate in the formation of pleural fluid [], renal AQP2 is involved in levels of solutes []and changes in AQP9 in the hippocampus are related to delayed neuronal death []. Aquaporins contain two tandem repeats, each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA).Aquaporin-11 (AQP11) and aquaporin-12 belong to a new aquaporin subfamily termed superaquaporins []. AQP11 is found in the endoplasmic reticulum and has been connected to policystic kidney disease through knock-out experiments []. It has also been shown that although the characteristic NPA motif may not be fully conserved in both tandem repeats, the molecule nevertheless preserves its water-transport function [].
The aquaporins (AQPs) are a family of integral membrane proteins composed of two subfamilies: the orthodox aquaporins, which transport only water, and the aquaglyceroporins, which transport glycerol, urea, or other small solutes []. AQP1 in pleural mesothelial cells participate in the formation of pleural fluid [], renal AQP2 is involved in levels of solutes []and changes in AQP9 in the hippocampus are related to delayed neuronal death []. Aquaporins contain two tandem repeats, each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA).Aquaporins 11 and 12 are classified as members of a new AQP subfamily: the subcellular AQPs []. AQP 11 and 12 appear to be more distantly related to the other mammalian aquaporins and aquaglyceroporins. AQP11 is functionally distinct from other proteins of the aquaporin superfamily and could represent a new aquaporin subfamily []. In members of the subcellular AQPs, one of the two asparagine-proline-alanine (NPA) motifs are not completely conserved. They play a crucial role in selective water conduction and function as water channels []. This group represents an aquaporin types 11 and 12.
The aquaporins (AQPs) are a family of integral membrane proteins composed of two subfamilies: the orthodox aquaporins, which transport only water, and the aquaglyceroporins, which transport glycerol, urea, or other small solutes []. AQP1 in pleural mesothelial cells participate in the formation of pleural fluid [], renal AQP2 is involved in levels of solutes []and changes in AQP9 in the hippocampus are related to delayed neuronal death []. Aquaporins contain two tandem repeats, each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA).Aquaporin-11 and aquaporin-12 (AQP12) belong to a new aquaporin subfamily termed superaquaporins []. AQP12 is exclusively found in pancreatic acinar cells [], and is not localised in the plasma membrane. No specific localisation has yet been established for this subfamily, but its presence in the pancreas implies some role in the secretion of digestive enzymes []and fluids in the pancreatic cells []. A structural characteristic of AQP12 is the lack of a cytoplasmic N-terminal region, by contrast with all other known aquaporins.
