Fig. 4

Structure alignment of ScTrk1 with its homologs with known structures. The alignment was based on a structural superposition of the crystal structures of BsKtrB (PDB code 4J7C [PMID: 23598340]) and VpTrkH (PDB code 3PJZ [PMID: 21317882]). The selectivity filters are marked by black asterisks, the three mutations by red asterisks, and the intramembrane loop is denoted as IML. For clarity, the extensive insert (residues 132-749) in the ScTrk1 sequence has been omitted. Red filled boxes indicate strict identity, and blue-framed boxes represent similarity across all aligned sequences