Fig. 1.

Schematic diagram of the oxytocin and vasopressin genes (large arrows), preprohormones (boxes), and neuropeptides (bottom). Their human chromosomal location is shown at the top. Both genes are composed of three exons shown as small blue arrows and separated by two introns (shown as dotted lines between the exons). The genes are located on the same chromosome but are transcribed in opposite directions and separated by an intergenic region (IGR). The IGR length varies across species. The preprohormones each contain a signal peptide (SP), a neuropeptide (Avp or Oxt), and a neurophysin (NP). In the case of Avp, a glycopeptide (GP) as well. Protein processing signals are represented by thick lines. Cysteine residues form a disulfide bond to create a cyclic six amino acid ring for both neuropeptides. Seven out of the nine amino acids are identical in the neuropeptides and two are different (red). Adapted and modified from (Caldwell et al., 2008).