In this first part of a review on recent insights into the structure and function of the γ-aminobuty rie acid type A - benzodiazepine receptor system, the γ-aminobutyric acid type A (GABAA) receptor and the different types of benzodiazepine (BDZ) receptors known at this moment are dicussed. GABAA- and BDZ receptors are coupled in a supramolecular GABAA-BDZ-ionophore receptor complex, each consisting of five acidic glycoprotein molecules called subunits. These subunits can be classified into five groups: α, β, γ, σ and ρ. Present evidence indicates the existence of multiple subtypes of these subunits. Multiple GABAA-BDZ receptors exist in the brain that show differential distribution and developmental patterns. These receptors differ from their subunit composition. The final functional properties of the receptor are determined by the different subunits constituting this receptor. Heterogeneity among α- subunits may determine the diversity of BDZ pharmacology in different regions of the nervous system.
