Figure 3. Structural organization of the Vasopressin-neurophysin II gene, and processing of its product. The AVP-NPII gene has 3 exons. Translation of the mRNA yields a larger preprohormone precursor, subsequently modified through substantial post-translational modification. The OT gene has a similar structure, and its product undergoes similar processing and post-translational modification. AVP: Vasopressin. NPII: Neurophysin II. OsRE: osmo-sensitive response element. GRE: glucocorticoid response element. ERE: estrogen response element. AP1-RE: AP1 response element.