Differential expression of two forms of GABAA receptor gamma 2-subunit in mice.

The gamma-aminobutyric acid type A (GABAA) receptor gamma 2-subunit is important for benzodiazepine action. In previous studies, two forms of gamma 2-subunit have been found which are generated by RNA alternative splicing (gamma 2L and gamma 2S) and differ by the presence or absence of an 8-amino acid insertion in the major intracellular loop between proposed transmembrane domains M3 and M4. We have used the RNase protection assay to study regulation of expression of the two forms of gamma 2-subunit in mouse brain, as judged from mRNA levels. We find that gamma 2L and gamma 2S are differentially expressed in brain regions and that gamma 2S is expressed at a fairly constant level during brain development while gamma 2L increases dramatically with maturation. Their differentially regulated expression suggests further that gamma 2L and gamma 2S form receptors with important functional differences.