INTRODUCTION: Apolipoprotein E (ApoE), reelin, and several other proteins bind ApoE-receptor 2 (apoER2), distinguished from other members of its receptor family by signal transduction which enhances the activity of N-methyl D-aspartate (NMDA) receptors. Evidence indicates that this signal transduction depends upon apoER2 forming dimers or other high-order clusters. It seems noteworthy therefore that protein products of major APOE gene variants differ in their numbers of cysteines capable of form...