Identification of the site of mutation within the M2 region of the GABA receptor of the cyclodiene-resistant German cockroach.

Abstract

The DNA and amino acid sequences of the membrane-spanning region of the GABA receptors of the German cockroach have been identified along with information on the nature and the specific site of mutation in the cyclodiene-resistant strains. In this resistant strain, the mutation has occurred at the most conserved, lower M2 cylinder region involving a G to T conversion, resulting in an amino acid change of alanine (GCC) residue to serine (TCC). The site, furthermore, coincides with the most conserved region of all GABA receptor subunits and the expected Cl- transporting segment constituting the innermost surface of the channel opening. The deduced sequence of the German cockroach GABA receptor differs from that of Drosophila mainly in the connecting region between M3 and M4.