title: Dopamine transporter endocytic determinants: carboxy terminal residues critical for basal and PKC-stimulated internalization.
abstract: Dopamine (DA) reuptake terminates dopaminergic neurotransmission and is mediated by DA transporters (DATs). Acute protein kinase C (PKC) activation accelerates DAT internalization rates, thereby reducing DAT surface expression. Basal DAT endocytosis and PKC-stimulated DAT functional downregulation rely on residues within the 587-596 region, although whether PKC-induced DAT downregulation reflects transporter endocytosis mechanisms linked to those controlling basal endocytosis rates is unknown. Here, we define residues governing basal and PKC-stimulated DAT endocytosis. Alanine substituting DAT residues 587-590 1) abolished PKC stimulation of DAT endocytosis, and 2) markedly accelerated basal DAT internalization, comparable to that of wildtype DAT during PKC activation. Accelerated basal DAT internalization relied specifically on residues 588-590, which are highly conserved among SLC6 neurotransmitter transporters. Our results support a model whereby residues within the 587-590 stretch may serve as a locus for a PKC-sensitive braking mechanism that tempers basal DAT internalization rates.
authors.affiliation: Interdisciplinary Graduate Program, University of Massachusetts Medical School, Worcester, MA 01655, USA.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Boudanova
authors.forename: Deanna M
authors.initials: DM
authors.lastname: Navaroli
authors.forename: Zachary
authors.initials: Z
authors.lastname: Stevens
authors.forename: Haley E
authors.initials: HE
authors.lastname: Melikian
mesh_terms: D000409:Alanine / Q000235:genetics; D000818:Animals; D019921:Biotinylation / Q000379:methods; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects* / Q000502:physiology; D016716:PC12 Cells; D011493:Protein Kinase C / Q000494:pharmacology*; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D014162:Transfection / Q000379:methods
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D011493:Protein Kinase C; D000409:Alanine; D004298:Dopamine