Phosphorylation of Adenylyl Cyclase III at Serine1076 Does Not Attenuate Olfactory Response in Mice

Feedback inhibition of adenylyl cyclase III (ACIII) via Ca2+-induced phosphorylation has long been hypothesized to contribute to response termination and adaptation of olfactory sensory neurons (OSNs). To directly determine the functional significance of this feedback mechanism for olfaction in vivo, we genetically mutated serine(1076) of ACIII, the only residue responsible for Ca2+-induced phosphorylation and inhibition of ACIII (Wei et al., 1996, 1998), to alanine in mice. Immunohistochemistry and Western blot analysis showed that the mutation affects neither the cilial localization nor the expression level of ACIII in OSNs. Electroolfactogram analysis showed no differences in the responses between wild-type and mutant mice to single-pulse odorant stimulations or in several stimulation paradigms for adaptation. These results suggest that phosphorylation of ACIII on serine(1076) plays a far less important role in olfactory response attenuation than previously thought.