GABAA/benzodiazepine receptors are formed by the assembly of presumably five polypeptides with unknown stoichiometry. Six alpha, three beta, two gamma, and one delta subunit have been characterized on the molecular level. In analogy to the nicotinic acetylcholine receptor, and supported by functional analysis of recombinantly expressed GABAA receptor subunits, a structure containing at least three different polypeptides has been proposed for the functional GABAA and benzodiazepine regulated Cl(-)-channel. Using an alpha 1 subunit specific antiserum we could show that additional alpha variants are present in alpha 1 subunit containing GABAA/Benzodiazepine receptor complexes. This suggests that the diversity of GABAA/Benzodiazepine receptors may be larger than previously thought.