Neuronal nicotinic acetylcholine receptor (AChR) subtypes have been defined pharmacologically, immunologically, and by DNA cloning, but the correlations between these approaches are incomplete. Vertebrate neuronal AChRs that have been isolated are composed of structural subunits and ACh‐binding subunits. A single kind of subunit can be used in more than one AChR subtype. Monoclonal antibody (mAb) 35 binds to structural subunits of subtypes of AChRs from both chicken brain and ganglia. By using antisera to a unique sequence of α3 ACh‐binding subunits expressed in bacteria, we show that ganglionic AChRs contain α3 ACh‐binding subunits, whereas the brain AChR subtype that binds mAb 35 does not. Subunit‐specific antisera raised against recombinant proteins should be a valuable approach for identifying the subunit composition of receptors in multigene, multisubunit families.