Human dopamine transporter gene variation: effects of protein coding variants V55A and V382A on expression and uptake activities.
The human dopamine transporter (DAT, SLC6A3) is an important 15 exon gene for dopamine neurotransmission and dopamine recycling. Common exon 15 variable number tandem repeat variants can be associated with attention deficit/hyperactivity disorder. Rarer single nucleotide polymorphisms produce missense variants including V55A and V382A. We now report studies of the functional influences of these DAT protein-coding variants. In COS cell transient-expression assays, V382A displays about half of the dopamine uptake velocity Vmax and cocaine analog binding Bmax values of wildtype DAT. V382A lowers dopamine's potency in inhibiting cocaine analog binding by six-fold. Cells expressing V382A or mixtures of V382A and wildtype DAT both display reduced plasma membrane and increased perinuclear expression, consistent with dominant effects of V328A on expression. V55A expresses normally but reveals a 1.7-fold-lower Km for dopamine uptake. Individuals with these human DAT protein variants could display altered dopamine systems.
Lin
Zhicheng
Z
Molecular Neurobiology Branch, NIDA-IRP, NIH, Nathan Shock Drive, Baltimore, MD, USA.
Uhl
George R
GR
D000409:Alanine / Q000235:genetics; D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D014644:Genetic Variation / Q000235:genetics* / Q000502:physiology; D006801:Humans; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D009419:Nerve Tissue Proteins; D016366:Open Reading Frames / Q000235:genetics*; D011485:Protein Binding / Q000235:genetics; D014633:Valine / Q000235:genetics
D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493214:SLC6A3 protein, human; D014633:Valine; D000409:Alanine; D004298:Dopamine