High impact information on AQP1

• To do this, we constructed an expression vector for a fusion protein consisting of the enhanced green fluorescent protein followed by an insertion site for AQP1 sequences and a C-terminal glycosylation tag [1].
• Here we examine the biogenesis of AQP1 in the human embryonic kidney cell line HEK-293T [1].
• AQP1 with the entire COOH tail of AQP2 was constitutively localized in the apical membrane, whereas chimeras with shorter COOH tail segments of AQP2 were localized in the apical and basolateral membrane [2].
• Localization of aquaporin (AQP) water channels to either apical or basolateral membranes is important for various epithelial functions [3].
• The water permeability in MDCK cells transfected with aquaporin 2 was an order of magnitude higher than in the intact MDCK cell line [4].

Biological context of AQP1

• However, dog and bovine AQP1 have only one N-glycosylation site, while two glycosylation sites were found in human and rodent AQP1 [5].
• The amino acid sequence in dog AQP1 was 91-94% identical to that in the other species mentioned above [5].
• Dog AQP1 has six predicted transmembrane domains, two NPA motifs, one mercury-sensitive site and four consensus phosphorylation sites, the same as the other species [5].
• In mammals, the regulation of water homeostasis is mediated by the aquaporin-1 (AQP1) water channel, which localizes to the basolateral and apical membranes of the early nephron segment, and AQP2, which is translocated from intracellular vesicles to the apical membrane of collecting duct cells after vasopressin stimulation [2].

Anatomical context of AQP1

• Xenopus oocytes injected with the mRNA of the dog AQP1 exhibited high water permeability in a hyposmotic medium [5].
• Complementary DNA of the water channel aquaporin 1 (AQP1) was cloned from dog kidney and erythroblasts [5].
• Thus, mature red blood cells from dog may have AQP1 in their cell membranes [5].
• The purpose of the present study was to determine if TEA blocks osmotic water flux of native AQP1 channels in kidney, and recombinant AQP1 channels expressed in a kidney derived MDCK cell line [6].

Associations of AQP1 with chemical compounds

• External TEA (10 mM) does not block the cGMP-dependent AQP1 ionic conductance, measured by two-electrode voltage clamp after pre-incubation of oocytes in 8Br-cGMP (10-50 mM) or during application of the nitric oxide donor, sodium nitroprusside (2-4 mM) [6].
• Tetraethylammonium chloride (TEA; 0.05 to 10 mM) was shown previously to inhibit the osmotic water permeability of human AQP1 channels expressed in Xenopus oocytes [6].
• BACKGROUND: Aquaporin-1 (AQP1) channels are constitutively active water channels that allow rapid transmembrane osmotic water flux, and also serve as cyclic-GMP-gated ion channels [6].

Analytical, diagnostic and therapeutic context of AQP1

• Molecular cloning and expression of aquaporin 1 [correction of aquapolin 1] (AQP1) in dog kidney and erythroblasts [5].

References