Demyelinated plaques in multiple sclerosis have decreased amounts of both myelin basic protein and sialosylgalactosylceramide (GM4), a ganglioside specifically localized in myelin and oligodendroglia of the central nervous system. We have found that myelin basic protein is capable of releasing large quantities of entrapped [14C]glucose from multilamellar liposomes containing GM4. If the conformation of GM4 in liposomal membranes resembles that of GM4 in its natural environment, basic protein and GM4 may be associated within the myelin sheath of the central nervous system and their interaction altered in demyelinating diseases such as multiple sclerosis.