Orexin (OX)

The polypeptides, named orexin A and orexin B, are derived from the same precursor (orexin) by proteolytic processing. The orexin-A peptide comprises gln33 to gly66, and the orexin-B peptide arg69 to met96, of the precursor protein. The predicted peptide for orexin A is identical in human, rat, mouse, and bovine. The predicted peptide for human orexin B shows only 2 amino acid differences when compared with the rodent sequence.

Preproorexin mRNA and immunoreactive orexin A are localized in neurons within and around the lateral and posterior hypothalamus in the adult rat brain. Northern blot analysis revealed that in the rat a 0.7-kb preproorexin mRNA species is expressed predominantly in the brain and in a small amount in testis.