CONSERVATION OF GAMMA-AMINOBUTYRIC-ACID TYPE-A RECEPTOR ALPHA-6 SUBUNIT GENE-EXPRESSION IN CEREBELLAR GRANULE CELLS

The gamma-aminobutyric acid type A receptor cDNAs encoding the alpha 6 subunit homologues from chicken and goldfish have been cloned and seq uenced. These proteins exhibit 83 and 75% identity, respectively, to t he rat alpha 6 polypeptide. In situ hybridization has demonstrated tha t, as in mammals, the avian and teleost fish alpha 6 subunit genes are predominately expressed in cerebellar granule cells. Correspondingly, flunitrazepam-nondisplaceable binding of [H-3]Ro 15-4513 (a benzodiaz epine partial inverse agonist), which is a major characteristic of gam ma-aminobutyric acid type A receptors that contain the alpha 6 polypep tide, is also mainly found for cerebellar granule cells of fish and ch ick. The conservation of this expression pattern suggests that gamma-a minobutyric acid type A receptors possessing the alpha 6 subunit are o f fundamental importance for cerebellar function and that the correspo nding gene regulatory elements, e.g., granule cell-specific enhancers, have also been conserved.