A Conserved Aspartic Acid Is Important for Agonist (VUAA1) and Odorant/Tuning Receptor-Dependent Activation of the Insect Odorant Co-Receptor (Orco)
Figure 1
Schematic diagram of DmelOrco showing aspartic acid residues present in TM domains 5 and 7 that are highly conserved in other insect species.
The TM domains and intracellular and extracellular regions of Dmel Orco were predicted using TMHMM [28], [29]. The green line indicates the presence of a myc-epitope at the N-terminus used to detect Orco by western blotting; to simplify comparison with the other Orco sequences we have retained the numbering of the WT DmelOrco protein. The red dots show Asp residues at positions 357 and 466 in TM5 and TM 7. The DmelOrco sequence was aligned using ClustalW with Orco sequences from various other species representing 6 insect orders. Sequences corresponding to TMs 5 and 7 are aligned; conserved Asp residues are shown in red. The Asp residue at position 357 is highly conserved; only the P. humus corporis sequence showed a difference; Asp is replaced by Glu. An Asp residue equivalent to D466 in DmelOrco is found in all sequences. The light gray shading shows absolutely conserved regions in TMs 5 and 7.The accession numbers for the Orco protein sequences are: Tribolium castaneum, EFA05687; Apis mellifera, NP_001128415; Helicoverpa zea, AAX14773; Bombyx mori, NP_001037060; Epiphyas postvittana, ACJ12928;Ceratitis capitata, AAX14775.1; Drosophila melanogaster, NP_524235; Anopheles gambiae, AAX14774; Lygus Hesperus, AFX73447; and Pediculus humanus corporis, EEB12924.