A novel invertebrate GABAA receptor-like polypeptide. Sequence and pattern of gene expression.

A full-length complementary DNA has been isolated, from the fresh-water mollusc Lymnaea stagnalis, that encodes a polypeptide (which we have named zeta) that exhibits between 30% and 40% identity to vertebrate GABAA and glycine receptor subunit sequences. The locations of seven introns have been determined in the corresponding gene and six of these occur at similar relative positions as those found in vertebrate GABAA receptor genes. RNase protection studies have revealed that the transcript for this Lymnaean polypeptide is present at highest levels in the adult nervous system but that it can also be detected in peripheral tissues.