Figure 6. Sequence alignment GluCl_crys and 5-HT3A and cartoon illustrating transmembrane region of GluCl_crys.

(A) Sequence alignment of the C-terminal region of mouse 5-HT3A receptor and GluCl_crys. The GluCl_crys M3 and M4 α helical membrane-spanning segments are indicated by the gray rectangles. The M3M4 loop region replaced by two alanines in the 5-HT3A-A₂ construct is shown underlined in bold. The 5-HT3A-A₂ construct yielded functional receptors with channel kinetics similar to wild type 5-HT3A receptors. Note that the 5-HT3A-A₂ construct lacks 16 residues aligned with the cytoplasmic end of the GluCl M4 segment. (B) Cartoon representation of the transmembrane domain of one subunit of GluCl (PDB: 3RHW). The cyan region at the cytoplasmic end of the M4 segment indicates the residues that were replaced by two alanine residues in the5-HT3A-A₂ construct.