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. 2020 May 9;9(10):e015751. doi: 10.1161/JAHA.119.015751

Figure 1. Structural and functional comparison of human and porcine TASK‐1 channels.

Figure 1

A, Left panel: Amino acid alignments of pTASK‐1 and hTASK‐1 show high similarity between human and porcine orthologs at the protein level. Differences are highlighted in red (*, conserved amino acids; :, amino acid substitutions by residues with similar properties). Right panel: Differences between human and porcine TASK‐1 are highlighted in a 3‐dimensional structure homology model of pTASK‐1 in red color. C‐termini were truncated because of lack of template sequences. B, Real‐time quantitative polymerase chain reaction experiments revealed similar atrial specific TASK‐1 expression patterns in human and porcine cardiac tissue. KCNK3 mRNA expression is presented relative to the housekeeping genes importin 8 (IPO8) or β‐actin (ACTB) in left atrial appendages (LAA), right atrial appendages (RAA) and the anterior wall of the left ventricle (LV) (n=5). C, Cloned human and porcine TASK‐1 ion channel subunits, heterologously expressed in Xenopus laevis oocytes, are inhibited by A293 (100 μmol/L) to a similar extent. Currents were recorded using two‐electrode voltage clamp technique measurements after application of the depicted pulse protocol. Quantification was performed at the end of the +20 mV pulse (n=3 cells). Representative current traces of hTASK‐1 and pTASK‐1 before (Control) and after application of A293 (100 μmol/L, 30 min) are indicated on the right side. Scalebars are given as inserts. D, In silico docking simulation of A293 in the inner channel pore of a pTASK‐1 homology model and magnified excerpts illustrate the interactions of A293 with the pore lining amino acids I118, L239 and N240. Data are presented as mean±SEM. **P<0.01 in Mann–Whitney tests. TASK‐1 indicates TWIK‐related acid‐sensitive K+ channel.