The encephalitogenic protein of myelin forms hexamers in which the polypeptides have a pleated-sheet structure

Sedimentation equilibrium data are shown to be consistent with the existence in solution of an equilibrium between monomers and hexamers of bovine myelin basic protein, without significant accumulation of intermediates. At low concentrations circular dichroism spectra were indicative of an aperiodic coiled secondary structure. At higher concentrations, where the protein self-associates, they showed formation of a beta-pleated sheet conformation. At low molar ratios myristoyllysophosphatidylcholine promotes protein self-association and the concomitant conformational transition. The data are consistent with the existence of an equilibrium mixture of relatively unstructured monomers and hexamers in which the polypeptides have a well-defined three-dimensional structure.