Peptides, opiate receptors, and cerebroside sulfate: An hypothesis

Abstract

1. 1. Evidence on the participation of cerebroside sulfate, an acidic glycolipid, in the structure and function of opiate receptors is reviewed and found to be somewhat contradictory. Some studies suggest that cerebroside sulfate is intimately involved in physiologically relevant opiate binding, while others suggest that the glycolipid is neither necessary nor sufficient to account for opiate binding properties. The latter studies favor a proteinaceous binding substance. 2. 2. An hypothesis is put forward to resolve this apparent disagreement. The opiate binding site is proposed to be a stable complex of acidic glycolipid coupled with a basic polypeptide on the order of 20 amino acids in length. Based on their primary and potential higher order structures, it is suggested that the polybasic endorphins (β-endorphin, dynorphin, α-neoendorphin), or derivatives of these compounds formed by limited N-terminal degradation, are likely candidates as opiate receptor components.