Alternative splicing of exons in T. castaneum cys-loop LGIC subunits. Equivalent alternate exons of T. castaneum and D. melanogaster cys-loop LGIC subunits are aligned. (A) Exon 4 splice variants in Tcasα4 and Dα4. The cysteine residues forming the cys-loop are marked by asterisks. (B) Splice variants of exons 3 and 8 in both Tcasα6 and Dα6. The glutamic acid residue located in the second transmembrane region (indicated as TM2) and involved in ion conductance  is underlined. (C) Splice variants of exons 3 and 6 in both Tcas_RDL and Drosophila RDL. Tribolium has an additional alternative for exon 3 (denoted Tcas_RDL exon 3c). (D) Exon 3 splice variants in Tcas_GluCl and Drosophila GluCl. Tribolium has an additional alternative exon (denoted Tcas_GluCl exon 3c). Throughout the figure, Tribolium residues that differ from those of the orthologous Drosophila exon are highlighted in bold and loops B to F, which contribute to ligand binding, are indicated.