A fascinating tail: cGMP activation of aquaporin-1 ion channels.
Aquaporin-1 (AQP1) is a member of the diverse major intrinsic protein family of water and solute channels. AQP1 is known as an osmotic water channel in kidney, brain, vascular system and other tissues, and recently has been demonstrated to function as a cation channel gated by cGMP. Electrophysiology and binding assays implicate direct cGMP binding in the AQP1 C-terminus and sequence similarities with cyclic-nucleotide-gated channels support the idea that the AQP1 C-terminus mediates ion channel activation. In this article, new data show that the AQP1 C-terminus also exhibits homology, at key residues, with the substrate-selectivity subdomain of cyclic nucleotide phosphodiesterases. Distinct pathways for fluxes of water and ions in the tetrameric AQP1 channel indicate an intriguing multifunctional capacity. The physiological role of AQP1 in transmembrane signaling remains to be elucidated for these channels expressed in native tissues.
Boassa
Daniela
D
Program in Neuroscience, University of Arizona, Tucson 85721, USA.
Yool
Andrea J
AJ
D000595:Amino Acid Sequence; D000818:Animals; D051398:Aquaporin 1; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001789:Blood Group Antigens; D006152:Cyclic GMP / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating; D007473:Ion Channels / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis
C496020:AQP1 protein, human; D020346:Aquaporins; D001789:Blood Group Antigens; D007473:Ion Channels; D051398:Aquaporin 1; D006152:Cyclic GMP