Cloning and characterization of the human urea transporter UT-A1 and mapping of the human Slc14a2 gene.
We have isolated and characterized the human homolog of the rat largest urea transporter of the UT-A family (hUT-A1). The 4.2-kb hUT-A1 cDNA encodes a 920-amino acid peptide, which is 89% identical to the rat UT-A1 protein. By Northern hybridization, hUT-A1 expression is detected in the human inner medulla as a approximately 4.4-kb mRNA transcript. By Western analysis, hUT-A1 is identified as a approximately 100-kDa protein in the human inner medulla. By immunohistochemistry, hUT-A1 expression is localized to the inner medullary collecting duct (IMCD). When transfected into HEK-293 cells hUT-A1 cDNA is translated into a approximately 98-kDa protein. Expression of hUT-A1 in Xenopus oocytes results in phloretin-inhibitable uptake of (14)C-urea, which shows only modest stimulation by cAMP, suggesting that in the human IMCD vasopressin may have a limited role in the short-term regulation of hUT-A1-mediated urea transport. We determined the organization of the human Slc14a2 gene and identified 20 exons distributed over approximately 67.5 kb on chromosome 18, from which hUT-A1 and the other human urea transporter, hUT-A2, are transcribed.
Bagnasco
S M
SM
Department of Pathology, Division of Nephrology, Emory University School of Medicine, 1639 Pierce Dr., Atlanta, GA 30322, USA. sbagnas@emory.edu
Peng
T
T
Janech
M G
MG
Karakashian
A
A
Sands
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D002460:Cell Line; D002874:Chromosome Mapping; D002887:Chromosomes, Human, Pair 18; D003001:Cloning, Molecular; D005091:Exons; D006801:Humans; D007679:Kidney Medulla / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000502:physiology; D008562:Membrane Glycoproteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014162:Transfection; D014508:Urea / Q000378:metabolism; D000096982:Urea Transporters
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D014508:Urea; D000096982:Urea Transporters