Functional characterization of the splicing variants of human norepinephrine transporter.
Human norepinephrine transporter (NET) displays three splicing variants having different carboxy terminals, hNET, hNET C-t var1 and hNET C-t var2. Functional characterization of these isoforms was performed with transient expression system in COS-7 cells. Cells transfected with hNET C-t var2, but not hNET C-t var1, revealed a significant increase in [(3)H]norepinephrine (NE) uptake and [(3)H]nisoxetine binding as well as hNET, in association with their different cellular localization indicated by immunostaining using NET-specific antisera. Kinetic and pharmacological analyses of [(3)H]NE uptake revealed different characteristics between hNET and hNET C-t var2. These results suggest that hNET C-t var2 may participate in NE transport in a manner different from hNET at noradrenergic synapses or in other tissues including placenta where NET variants were found to exist.
Kitayama
S
S
Department of Pharmacology, Faculty of Dentistry, Hiroshima University, Hiroshima 734-8553, Japan. shigeok@hiroshima-u.ac.jp
Morita
K
K
Dohi
T
T
D018759:Adrenergic Uptake Inhibitors / Q000378:metabolism; D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D019556:COS Cells / Q000187:drug effects / Q000378:metabolism; D002451:Cell Compartmentation / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D005473:Fluoxetine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D009420:Nervous System / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D050484:Norepinephrine Plasma Membrane Transport Proteins; D020033:Protein Isoforms / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011869:Radioligand Assay; D027981:Symporters / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*
D018759:Adrenergic Uptake Inhibitors; D050484:Norepinephrine Plasma Membrane Transport Proteins; D020033:Protein Isoforms; C493227:SLC6A2 protein, human; D027981:Symporters; D005473:Fluoxetine; C011386:nisoxetine; D009638:Norepinephrine