BACKGROUND: Insect odorant receptors (ORs) function as odorant-gated ion 
channels consisting of a conventional, odorant-binding OR and the Orco 
coreceptor. While Orco can function as a homomeric ion channel, the role(s) of 
the conventional OR in heteromeric OR complexes has largely focused only on 
odorant recognition.
RESULTS: To investigate other roles of odorant-binding ORs, we have employed 
patch clamp electrophysiology to investigate the properties of the channel pore 
of several OR complexes formed by a range of different odorant-specific 
Anopheles gambiae ORs (AgOrs) each paired with AgOrco. These studies reveal 
significant differences in cation permeability and ruthenium red susceptibility 
among different AgOr complexes.
CONCLUSIONS: With observable differences in channel function, the data support a 
model in which the odorant-binding OR also affects the channel pore. The 
variable effect contributed by the conventional OR on the conductive properties 
of odorant-gated sensory channels adds additional complexity to insect olfactory 
signaling, with differences in odor coding beginning with ORs on the periphery 
of the olfactory system.