A conserved asparagine residue in transmembrane segment 1 (TM1) of serotonin transporter dictates chloride-coupled neurotransmitter transport

J Biol Chem. 2011 Sep 2;286(35):30823-30836. doi: 10.1074/jbc.M111.250308. Epub 2011 Jul 5.

Abstract

Na(+)- and Cl(-)-dependent uptake of neurotransmitters via transporters of the SLC6 family, including the human serotonin transporter (SLC6A4), is critical for efficient synaptic transmission. Although residues in the human serotonin transporter involved in direct Cl(-) coordination of human serotonin transport have been identified, the role of Cl(-) in the transport mechanism remains unclear. Through a combination of mutagenesis, chemical modification, substrate and charge flux measurements, and molecular modeling studies, we reveal an unexpected role for the highly conserved transmembrane segment 1 residue Asn-101 in coupling Cl(-) binding to concentrative neurotransmitter uptake.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Asparagine / chemistry*
  • Chlorides / chemistry*
  • Cysteine / chemistry
  • Electrophysiology / methods
  • HeLa Cells
  • Humans
  • Ions
  • Mutagenesis, Site-Directed
  • Neurotransmitter Agents / metabolism*
  • Norepinephrine / metabolism
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Plasmids / metabolism
  • Rats
  • Serotonin / metabolism
  • Serotonin Plasma Membrane Transport Proteins / chemistry*
  • Xenopus laevis

Substances

  • Chlorides
  • Ions
  • Neurotransmitter Agents
  • Serotonin Plasma Membrane Transport Proteins
  • Serotonin
  • Asparagine
  • Cysteine
  • Norepinephrine