[Difference in the maturation of the three-domain vasopressin precursor in the guinea-pig and rat: identification of a neurophysin-copeptin fragment in the guinea pig].

Vasopressin, MSEL-neurophysin and copeptin have been isolated from guinea pig and rat neurophypophyses and their amino acid sequences have been determined. Whereas in rat processing of the three-domain precursor is complete, in the guinea pig a 132-residue fragment including MSEL-neurophysin and copeptin linked by an arginine residue has been characterized. This incomplete maturation (20% of the precursor) could be due to a deletion of an acidic residue in guinea pig copeptin when compared with other mammalian copeptins.