Aquaporins

Literature References: Group of integral membrane proteins that function as molecular water channels to facilitate osmotic movement of water across the plasma membrane. Found in plant and animal cells characterized as having high osmotic water permeability. Part of the MIP family of channel proteins, typified by the major intrinsic protein of the eye, that are responsible for the permeability of ions and small molecules. Homologs exhibit ~40% sequence identity. Structure consists of six transmembrane domains with 5 connecting loops; the water pore is thought to be formed by the juxtaposition of 2 highly conserved Asn-Pro-Ala (NPA) sequences within the lipid bilayer. Isoln of aquaporin-1 from human erythrocytes and renal tubules: B. M. Denker et al., J. Biol. Chem. 263, 15634 (1988). Cloning and sequence homology with MIP family: G. M. Preston, P. Agre, Proc. Natl. Acad. Sci. USA 88, 11110 (1991). Identification of function as membrane water channel: G. M. Preston et al., Science 256, 385 (1992). Nomenclature: P. Agre et al., Am. J. Physiol. 265, F461 (1993). Molecular structure: J. S. Jung et al., J. Biol. Chem. 269, 14648 (1994). Review of structure and tissue distribution: C. H. van Os et al., Biochim. Biophys. Acta 1197, 291-309 (1994); M. J. Chrispeels, P. Agre, Trends Biochem. Sci. 19, 421-425 (1994). Review of aquaporins in plants: M. J. Chrispeels, C. Maurel, Plant Physiol. 105, 9-13 (1994). Review of role in renal water transport: A. F. van Lieburg et al., Pediatr. Nephrol. 9, 228-234 (1995); of model for water permeation: T. Zeuthen, Trends Biochem. Sci. 26, 77-79 (2001); of function and physiology in the kidney: S. Nielsen et al., Physiol. Rev. 82, 205-244 (2002).