Concentrative nucleoside transporter (rCNT1) is targeted to the apical membrane through the hepatic transcytotic pathway.
The Na+-dependent nucleoside transporter CNT1 has been identified in a caveolin-enriched plasma membrane fraction (CEF), in transcytotic endosomes, and in canalicular membranes isolated from quiescent rat liver in which the transporter appears to be biologically active. CNT1 was also detected, albeit in small amounts, in the early/sorting endosomes. Plasma membrane preparations enriched in basolateral markers showed Na+-dependent nucleoside transport activity that is mostly, if not exclusively, accounted for by CNT2, a transporter protein which was not detected in CEF nor in the endosomal fractions. These data are consistent with different localization and trafficking pathways of the two isoforms in hepatocytes. CNT1 is the first transporter which is reported to follow the transcytotic pathway to be inserted on the apical side of liver parenchymal cells.
Duflot
Sylvie
S
Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, E-08028, Barcelona, Spain.
Calvo
Maria
M
Casado
F Javier
FJ
Enrich
Carlos
C
Pastor-Anglada
Marçal
M
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D015153:Blotting, Western; D021941:Caveolae / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D010957:Plasmids; D020033:Protein Isoforms / Q000378:metabolism; D011684:Purine Nucleosides / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism
D026901:Membrane Transport Proteins; D020033:Protein Isoforms; D011684:Purine Nucleosides; D011994:Recombinant Proteins; C065171:cif nucleoside transporter