in the same receptors (for review see Sieghart and Sperk, 2002). From these results a subunit stoichiometry of 2α, 2β and 1γ or 1δ subunit can be deduced for native receptors. This conclusion was confirmed in several recombinant receptor studies, some of which also were able to determine the subunit arrangement of receptors composed of 2α, 2βand 1γ subunit (Tretter et al., 1997; Baumann et al., 2002).
