Screening of Epilepsy-Linked Gabaa Receptor Mutants for Assembly Defects

Abstract

GABAA receptors (GABAARs) belong to the family of pentameric ligand-gated ion channels (pLGICs) and are the most important mediators of rapid inhibitory signals in the human brain. GABAARs are mostly heteropentamers (rarely homopentamers) that assemble from a repertoire of up to 19 different subunits. Mutations in three subunits, α1, β3 and γ2, are particularly frequently associated with epilepsy syndromes. Here, we generated 36 mutants of α1, β3 or γ2 subunits reported in the literature to be epilepsy-associated. Following their expression in Xenopus laevis oocytes, we examined their heteropentameric assembly and abundance at the plasma membrane using blue native PAGE (BN-PAGE) and SDS-PAGE, respectively. We provide an overview, which of the 36 mutations are associated with disturbed biosynthesis, heteropentameric assembly and/or impaired plasma membrane appearance. We hope that the knowledge of specific assembly defects resulting from point mutations may be helpful in developing targeted drug therapies for at least some of the mutations.