The N‐terminal acidic residue of the cytosolic helix 8 of an odorant receptor is responsible for different response dynamics via G‐protein

We previously observed highly rapid and robust response of murine olfactory receptor S6 (mOR‐S6) with chimeric Gα 15_olf , compared to Gα 15 . To identify residues responsible for this difference in response, mutations of the cytosolic helix 8 were analyzed in a heterologous functional expression system. The N‐terminal hydrophobic core between helix 8 and TM1–2 of mOR‐S6 is important for activation of both Gα 15_olf and Gα 15 . Point mutation of a helix 8 N‐terminal acidic residue eliminated the differences in response dynamics via Gα. This result suggests that an N‐terminal acidic residue of helix 8 is responsible for rapid response via Gα 15_olf .