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J Biol Chem October 25, 2002; 277 (43): 40610-6.

Cloning and functional characterization of a novel aquaporin from Xenopus laevis oocytes.

Virkki LV , Franke C , Somieski P , Boron WF .

We have cloned a novel aquaporin (AQP) from Xenopus laevis oocytes, which we have provisionally named AQPxlo. The predicted protein showed highest homology (39-50%) to aquaglyceroporins. Northern blot analysis showed strong hybridization to an approximately 1.4-kb transcript in X. laevis fat body and oocytes, whereas a weaker signal was obtained in kidney. We injected in vitro transcribed cRNA encoding AQPxlo into Xenopus oocytes for functional characterization. AQPxlo expression increased osmotic water permeability (P(f)), as well as the uptake of glycerol and urea. However, AQPxlo excluded larger polyols and thiourea. An alkaline extracellular pH (pH(o)) increased P(f) and to a lesser extent urea uptake but not glycerol uptake. Remarkably, low HgCl(2) concentrations (0.3-10 microm) reduced P(f) and urea uptake, whereas high concentrations (300-1000 microm) reversed the inhibition. We propose that AQPxlo is a new AQP paralogue unknown in mammals.

PubMed ID: 12192003
Article link: J Biol Chem

Species referenced: Xenopus laevis
Genes referenced: aqp1 aqp10 aqp3 aqp7
GO keywords: water channel activity [+]

Article Images: [+] show captions