Molecular cloning, functional expression and chromosomal
localization of cdnas encoding a human na+/nucleoside cotransporter
(hcnt1) .
Ritzel, Mabel W. L., Sylvia Y. M. Yao, Mei-Yi Huang, John F. Elliott,
Carol E. Cass, and James D. Young.
Membrane Transport Group, Departments of Physiology, Biochemistry,
Oncology and Medical Microbiology and Immunology, Medical Sciences
Building, University of Alberta, Edmonton, Alberta, Canada T6G
2H7
APStracts 3:0315C, 1996.
We report identification of a new human nucleoside transporter protein
by molecular cloning and functional expression of its cDNA.
Previously, we used expression selection in Xenopus oocytes to
isolate a cDNA from rat jejunal epithelium encoding the pyrimidine
-selective Na+-dependent nucleoside transporter rCNT1 (Huang, Q.Q. et
al (1994) J. Biol. Chem. 269, 17757-17760). cDNAs for a human homolog
of rCNT1, designated hCNT1, have now been isolated from human kidney
by hybridization cloning and reverse transcriptase polymerase chain
reaction amplification strategies. hCNT1 was 83% identical to rCNT1
in amino acid sequence and exhibited the transport characteristics of
a Na+-dependent nucleoside transporter with selectivity for
pyrimidine nucleosides and adenosine when expressed in Xenopus
oocytes. Deoxyadenosine, which undergoes net renal secretion, and
guanosine were poor permeants. hCNT1 did, however, transport 3'
-azido-3'-deoxythymidine. This is the first demonstration that members
of the CNT family exist in human cells and provides evidence of their
involvement in the renal transport of physiological nucleosides and
nucleoside drugs. The hCNT1 gene was mapped to chromosome 15q25-26.
Received 14 May 1996; accepted in final form 23 September 1996.
APS Manuscript Number C263-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996