Stimulation-dependent changes in oligomeric conformationof serotonin 5-HT receptors
An increasing number of G protein-coupled receptors (GPCRs) have been shown to form oligomeric units in the plasma membrane. In many cases there is evidence that this oligomerization can result in altered receptor pharmacology, desensitization and traffi cking. These alterations can consequently result in different effects in intracellular signalling, thus diversifying the functional role of a GPCR. The serotonin (5-HT)1A receptor is a GPCR involved in multiple processes, among which, the regulation of neurogenesis, respiratory control, as well as depression and anxiety states have found the most interest. Biochemical experiments performed in N1E-115 neuroblastoma cells have suggested that 5-HT1A receptors form homooligomers. Acceptor-photobleaching allows for the direct measurement of apparent FRET between the fl uorophores of CFP- and YFP-tagged proteins, further suggesting some specifi c interaction between the receptors. Furthermore, with the use a novel FRET quantifi cation method, we have also been able to discriminate between specifi c and random proteinprotein interaction and to verify dynamics of homo- and heterooligomerization between 5-HT1A and 5-HT7 receptors.