Localization of the ?1- and ?2-subunit messenger RNAs in chick retina by in situ hybridization predicts the existence of ?-aminobutyric acid type C receptor subtypes
We have amplified partial complementary {DNAs} for the chicken ?-aminobutyric acid type C (GABAC) receptor ?1 and ?2 subunits using the polymerase chain reaction. These nucleotide sequences have been utilized to design specific oligonucleotide probes for the in situ hybridization localization of the corresponding messenger {RNAs} (mRNAs) in the 1-day-old chick retina. Although both transcripts are found almost exclusively in the inner nuclear layer, their distributions differ markedly. From the locations of the hybridization signals, we deduce that the ?1-subunit mRNA is present mainly in bipolar cells and that the ?2-subunit mRNA is present in both amacrine and horizontal cells. These results suggest that the ?1 and ?2 subunits frequently occur in different receptor complexes and, therefore, that subtypes of the {GABAC} receptor exist
