Conducting states of a mammalian serotonin transporter

Neuron. 1994 Apr;12(4):845-59. doi: 10.1016/0896-6273(94)90337-9.


We have studied permeation at a cloned rat 5-HT transporter expressed in Xenopus oocytes. [3H]5-HT uptake and [125I]RTI-55 binding yield a turnover rate of approximately 1/s that does not depend on membrane potential. However, in voltage-clamp experiments, three distinct currents results from 5-HT transporter expression. First, a steady-state, voltage-dependent transport-associated current is induced by 5-HT application. Second, a transient inward current is activated by voltage jumps to high negative potentials in the absence of 5-HT and is blocked by 5-HT itself. Third, a small leakage current is observed in the absence of 5-HT. All the observed currents are blocked by inhibitors of 5-HT uptake but are differentially affected by Na+, Li+, K+, Ba2+, Cs+, Cl-, and amiloride. The conducting states of the 5-HT transporter may reflect the existence of a permeation pathway similar to that of ionic channels.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amiloride / pharmacology
  • Animals
  • Anions
  • Carrier Proteins / genetics
  • Carrier Proteins / physiology*
  • Cations
  • Cocaine / analogs & derivatives
  • Cocaine / metabolism
  • Electric Conductivity
  • Female
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / physiology*
  • Membrane Potentials / physiology
  • Membrane Transport Proteins*
  • Metals / pharmacology
  • Nerve Tissue Proteins*
  • Oocytes / metabolism
  • Rats
  • Recombinant Proteins
  • Serotonin / metabolism
  • Serotonin / pharmacology
  • Serotonin Plasma Membrane Transport Proteins
  • Tritium
  • Xenopus


  • Anions
  • Carrier Proteins
  • Cations
  • Membrane Glycoproteins
  • Membrane Transport Proteins
  • Metals
  • Nerve Tissue Proteins
  • Recombinant Proteins
  • Serotonin Plasma Membrane Transport Proteins
  • Slc6a4 protein, rat
  • Tritium
  • Serotonin
  • 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane
  • Amiloride
  • Cocaine