title: PC12 variants deficient in norepinephrine transporter mRNA have wild type activities of several other related transporters.
abstract: Wild type PC12 pheochromocytoma cells express a Na(+)-dependent norepinephrine transporter that operates in the uptake of catecholamines. In addition to the previously described Na(+)-dependent system A for the uptake of alpha-amino-isobutyric acid and system Gly for glycine, we have identified two other Na(+)-dependent transporter systems for amino acid uptake in these cells: 1) system beta for beta-alanine and taurine; and 2) a system for creatine. Uptake of alpha-amino-isobutyric acid, glycine, beta-alanine, and creatine is not affected in some PC12 variants that were previously shown to be deficient in catecholamine uptake and to have decreased levels of norepinephrine transporter mRNA. We have isolated two PC12 cDNA clones that are essentially identical in sequence to recently reported cDNAs for rat brain taurine and creatine transporters, respectively, and a third cDNA that appears to code for a novel transporter. mRNAs for these three transporters are present at wild type levels in those variants that express no or little norepinephrine transporter mRNA. These results support the notion that the expression of catecholamine reuptake transporters may be particularly susceptible to down-regulation.
authors.affiliation: Department of Biological Chemistry, School of Medicine, University of California, Los Angeles 90024.
authors.forename: K
authors.initials: K
authors.lastname: Houben
authors.forename: K
authors.initials: K
authors.lastname: Dardashti
authors.forename: B D
authors.initials: BD
authors.lastname: Howard
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D002999:Clone Cells; D003401:Creatine / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D015870:Gene Expression; D014644:Genetic Variation; D007700:Kinetics; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D050484:Norepinephrine Plasma Membrane Transport Proteins; D009928:Organ Specificity; D016716:PC12 Cells; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D027981:Symporters
chemical_list: D000596:Amino Acids; D002352:Carrier Proteins; D050484:Norepinephrine Plasma Membrane Transport Proteins; D012333:RNA, Messenger; C493226:Slc6a2 protein, rat; D027981:Symporters; D003401:Creatine; D004298:Dopamine; D009638:Norepinephrine