title: High-affinity, equilibrative nucleoside transporter of pig kidney cell line (PK-15).
abstract: Nucleoside transport was determined in the cloned porcine kidney cell line PK-15 which exhibits properties of tubular cells. The cells did not express any Na(+)-dependent, concentrative nucleoside transport. They exhibited only nitrobenzylthioinosine-sensitive equilibrative nucleoside transport. Their transport activity, however, was only about 10% of that observed in many other mammalian cell lines. This low transport activity correlated with a relatively low number of high-affinity nitrobenzylthioinosine binding sites (5 x 10(3)/cell). Furthermore, although the equilibrative transporter of PK-15 cells exhibited a similar broad substrate specificity as the equilibrative nucleoside transporters of other mammalian cells, it exhibited a much higher affinity for certain nucleosides, especially cytidine and uridine, than the latter. The Michaelis-Menten constants for zero-trans transport and equilibrium exchange of uridine in ATP-depleted cells were about the same (about 40 microM), indicating equal mobility of the nucleoside-loaded and empty carrier. Concentrative nucleoside transport was detected in one set of PK-15 cultures, but was found to be due to mycoplasma contamination.
authors.affiliation: Department of Microbiology, University of Minnesota Medical School, Minneapolis 55455.
authors.forename: J M
authors.initials: JM
authors.lastname: Aran
authors.forename: P G
authors.initials: PG
authors.lastname: Plagemann
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D004176:Dipyridamole / Q000494:pharmacology; D005573:Formycins / Q000378:metabolism; D006096:Gramicidin / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D033703:Nucleoside Transport Proteins; D013552:Swine; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D005573:Formycins; D008565:Membrane Proteins; D033703:Nucleoside Transport Proteins; C034561:formycin B; D006096:Gramicidin; D013868:Thioinosine; D004176:Dipyridamole; D000255:Adenosine Triphosphate; C001789:4-nitrobenzylthioinosine