Cyclic nucleotides weakly activate the BmOr-1-BmOrco complex from outside of the cell.

<p>(A) Summary of the average responses of BmOr-1-BmOrco-injected oocytes (left) and none-injected oocytes (right) to various cyclic nucleotide reagents (100 µM). Each response was normalized by the response amplitude of BmOr-1-BmOrco-injected oocytes to 10 µM bombykol. The bar graphs show mean ± S.E.M. from 3–4 independent oocytes. (B) Representative current traces of oocytes expressing BmOr-1-BmOrco in response to bombykol and various concentrations of cyclic nucleotides. Bombykol was applied to the oocytes at the time indicated by the arrowhead (for 5 sec), and cyclic nucleotides were applied during the time indicated by colored square (for 30 sec), respectively. Concentrations of ligands were as follows: bombykol, 10 µM, cyclic nucleotides, 100 nM, 1 µM, 10 µM, 100 µM. (C) Dose-dependent responses of BmOr-1-BmOrco to cAMP (yellow) or cGMP (blue). Each point represents the mean current ± S.E.M. from 3 independent oocytes. Each response was normalized to the response to 10 µM bombykol. (D) Representative current traces of oocytes expressing rat olfactory cyclic nucleotide-gated channel complex (CNGA2+A4+B1b) in response to 8-Br-cGMP or cGMP (100 µM). n = 4. (E) Current-voltage relationships of oocytes expressing BmOr-1-BmOrco in response to bombykol (black), cGMP (blue), and cAMP (yellow).