Aims: Tandem pore potassium channels (K2P) are expressed in neuronal tissue and regulate cellular excitability. Furthermore, they play a role in mood disorders like depression and are molecular targets of clinically used antidepressants. In our study we characterize the interaction site of one member of the K2P subfamily, TREK-1, with the selective serotonin reuptake inhibitor fluoxetine. Methods: Transcripts of TREK-1 wildtype and TREK-1 deletion mutant lacking the first 52 amino acids were heterologously expressed in Xenopus oocytes. Differences in antidepressant sensitivity of TREK-1[wt] and TREK-1[DN52] currents were measured using two-electrode voltage-clamp recordings and variable translation initiation was detected by Western immunoblotting. Results: TREK-1 displays an outward rectifying current-voltage relation and currents averaged 5.19 mA ± 3.6 mA (n=40) at a holding potential of +30 mV. Application of Fluoxetine (1 mM) maximally reduced the current amplitude by 76.4 %± 2.62 % (n=21). The same was true for other clinically used antidepressants like Maprotlin (-77.4 %± 4.24%), Citalopram (-70.8 %± 3.1%), and Mirtazapin (-64.6 %± 4.3 %), respectively. Currents through TREK-1[DN52] amounted to 3.0 mA ± 0.8 mA (n=27) and, in contrast to TREK-1 [wt], were maximally reduced only by 23.2 %± 5.6 % (n=21) upon application of Fluoxetine (1 mM). Conclusion: We identified the interaction site of clinically used antidepressants with K2P potassium channels at the N-terminus of the protein. This finding is of particular importance because in the central nervous system two isoforms of TREK-1, a full-length TREK-1 protein with 426 amino-acids as well as a short polypeptide lacking the first 52 amino-acids are expressed in neuronal cells. Both isoforms arise from a cellular mechanism based on alternative translation initiation.