The γ-aminobutyric acid type A receptor cDNAs encoding the α6 subunit homologues from chicken and goldfish have been cloned and sequenced. These proteins exhibit 83 and 75% identity, respectively, to the rat α6 polypeptide. In situ hybridization has demonstrated that, as in mammals, the avian and teleost fish α6 subunit genes are predominately expressed in cerebellar granule cells. Correspondingly, flunitrazepam-nondisplaceable binding of [3H]Ro 15-4513 (a benzodiazepine partial inverse agonist), which is a major characteristic of γ-aminobutyric acid type A receptors that contain the α6 polypeptide, is also mainly found for cerebellar granule cells of fish and chick. The conservation of this expression pattern suggests that γ-aminobutyric acid type A receptors possessing the α6 subunit are of fundamental importance for cerebellar function and that the corresponding gene regulatory elements, e.g., granule cell-specific enhancers, have also been conserved.