Molecular and functional characterization of an amphibian urea transporter.
We report the characterization of a frog (Rana esculenta) urea transporter (fUT). The cloned cDNA is 1.4 kb long and contains a putative open reading frame of 1203 bp. In frog urinary bladder, the gene is expressed as two mRNAs of 4.3 and 1.6 kb. The fUT protein is 63.1 and 56.3% identical to rat UT-A2 and UT-B1, respectively. The internal duplication of UT-A2 and UT-B, as well as the double LP box urea transporter signature sequence were found in this amphibian urea transporter. When expressed in Xenopus oocytes, fUT induced a 10-fold increase in urea permeability, which was blocked by both phloretin and mercurial reagents. The fUT protein did not transport thiourea, but the fUT-mediated urea transport was strongly inhibited by this compound. Thus, this amphibian urea transporter displays transport characteristics in between those of UT-A2 and UT-B.
Couriaud
C
C
Service de Biologie Cellulaire, Bât. 532, CEA/Saclay, 91191, Gif-sur-Yvette, France.
Leroy
C
C
Simon
M
M
Silberstein
C
C
Bailly
P
P
Ripoche
P
P
Rousselet
G
G
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D015723:Gene Library; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009865:Oocytes; D011893:Rana esculenta; D016415:Sequence Alignment; D014508:Urea / Q000378:metabolism*; D001743:Urinary Bladder / Q000378:metabolism; D014981:Xenopus; D000096982:Urea Transporters
D002352:Carrier Proteins; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D014508:Urea; D000096982:Urea Transporters