Insulin binding to human placenta membranes treated at pH 7.6 or 8.5 in the presence or absence of 2.0 mM DTT for 5 min, followed by the simultaneous removal of the DTT and pH adjustment to pH 7.6, displayed curvilinear (heterogeneous) insulin binding plots when analyzed by the method of Scatchard. However, Triton X-100 solubilization followed by Bio-Gel A-1.5m gel filtration chromatography of the placenta membranes previously treated with DTT at pH 8.5 generated a nearly straight line (homogeneous) Scatchard plot. 125I-insulin affinity crosslinking studies coupled with Bio-Gel A-1.5m gel filtration chromatography demonstrated that the alkaline pH and DTT treatment of placenta membranes followed by detergent solubilization generated an alpha beta heterodimeric insulin receptor complex from the alpha 2 beta 2 heterotetrameric disulfide-linked state. The ability of alkaline pH and DTT to produce a functional alpha beta heterodimeric insulin receptor complex was found to be time dependent with maximal formation and preservation of tracer insulin binding occurring at 5 min. These data demonstrate that (i) a combination of alkaline pH and DTT treatment of placenta membranes can result in the formation of a functional alpha beta heterodimeric insulin receptor complex. (ii) the alpha beta heterodimeric complex displays homogeneous insulin binding. (iii) the insulin receptor membrane environment maintains the alpha 2 beta 2 association state, which displays heterogeneous insulin binding, despite reduction of the critical domains that are responsible for the covalent interaction between the alpha beta heterodimers.