Single Molecule Analysis Reveals Coexistence of Stable Serotonin Transporter Monomers and Oligomers in the Live Cell Plasma Membrane [Neurobiology]

January 6th, 2014 by Anderluh, A., Klotzsch, E., Reismann, A. W. A. F., Brameshuber, M., Kudlacek, O., Newman, A. H., Sitte, H. H., Schutz, G. J.

The human serotonin transporter (hSERT) is responsible for the termination of synaptic serotonergic signaling. While there is solid evidence that SERT forms oligomeric complexes, the exact stoichiometry of the complexes and the fractions of different co-existing oligomeric states still remain enigmatic. Here we used single molecule fluorescence microscopy to obtain the oligomerization state of the SERT via brightness analysis of single diffraction limited fluorescent spots. Heterologously expressed SERT was labeled either with the fluorescent inhibitor JHC 1-64, or via fusion to mGFP. We found a variety of oligomerization states of membrane-associated transporters, revealing molecular associations larger than dimers and demonstrating the coexistence of different degrees of oligomerization in a single cell; the data is in agreement with a linear aggregation model. Furthermore, oligomerization was found to be independent of SERT surface density and oligomers remained stable over several minutes in the live cell plasma membrane. Together, the results indicate kinetic trapping of preformed SERT oligomers at the plasma membrane.
  • Posted in Journal of Biological Chemistry, Publications
  • Comments Off on Single Molecule Analysis Reveals Coexistence of Stable Serotonin Transporter Monomers and Oligomers in the Live Cell Plasma Membrane [Neurobiology]