Reelin is a covalent dimer. a) Recombinant reelin samples were prepared by adding SDS-PAGE buffer with or without DTT or boiling prior to loading in duplicate on a 6.5% acrylamide gel with 4% stacking gel, reacted with antibody 142. 1 no DTT, no boiling; 2 no DTT, 3 min boiling ; 3 DTT, no boiling ; 4 DTT, 3 min boiling. b) Immunoblot of proteins prepared by adding SDS-PAGE buffer without DTT but with 3 min boiling, loaded on an agarose-acrylamide composite gel. Lanes 1–3, reacted with antibody 142. 1 recombinant reelin, 2 human plasma, 3 human serum, 4 laminin, reacted with anti-laminin antibody.