Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/47279
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Type: | Journal article |
Title: | Single amino acids in the carboxyl terminal domain of aquaporin-1 contribute to cGMP-dependent ion channel activation |
Author: | Boassa, D. Yool, A. |
Citation: | BMC Physiology, 2003; 3(Article 1):1-13 |
Publisher: | BioMed Central Ltd. |
Issue Date: | 2003 |
ISSN: | 1472-6793 1472-6793 |
Abstract: | BACKGROUND Aquaporin-1 (AQP1) functions as an osmotic water channel and a gated cation channel. Activation of the AQP1 ion conductance by intracellular cGMP was hypothesized to involve the carboxyl (C-) terminus, based on amino acid sequence alignments with cyclic-nucleotide-gated channels and cGMP-selective phosphodiesterases. RESULTS Voltage clamp analyses of human AQP1 channels expressed in Xenopus oocytes demonstrated that the nitric oxide donor, sodium nitroprusside (SNP; 3–14 mM) activated the ionic conductance response in a dose-dependent manner. Block of soluble guanylate cyclase prevented the response. Enzyme immunoassays confirmed a linear dose-dependent relationship between SNP and the resulting intracellular cGMP levels (up to 1700 fmol cGMP /oocyte at 14 mM SNP). Results here are the first to show that the efficacy of ion channel activation is decreased by mutations of AQP1 at conserved residues in the C-terminal domain (aspartate D237 and lysine K243). CONCLUSIONS These data support the idea that the limited amino acid sequence similarities found between three diverse classes of cGMP-binding proteins are significant to the function of AQP1 as a cGMP-gated ion channel, and provide direct evidence for the involvement of the AQP1 C-terminal domain in cGMP-mediated ion channel activation. |
Keywords: | Oocytes Animals Xenopus laevis Humans Nitroprusside Amino Acids Peptides Aquaporins Ion Channels Cyclic GMP Nitric Oxide Donors Blood Group Antigens Patch-Clamp Techniques Mutagenesis, Site-Directed Amino Acid Sequence Conserved Sequence Protein Structure, Tertiary Membrane Potentials Dose-Response Relationship, Drug Osmotic Pressure Female Aquaporin 1 Cyclic Nucleotide-Gated Cation Channels |
Rights: | © 2003 Boassa and Yool; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL. |
DOI: | 10.1186/1472-6793-3-12 |
Published version: | http://www.biomedcentral.com/1472-6793/3/12 |
Appears in Collections: | Aurora harvest Molecular and Biomedical Science publications |
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hdl_47279.pdf | Published version | 443.25 kB | Adobe PDF | View/Open |
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