Entry retrieved from the Protein Data Bank at RCSB.

1NPO Complex (Hormone Transport Hormone). Date Feb 01, 1996.
Title: Bovine Neurophysin II Complex With Oxytocin
Authors:J.P.Rose, C.K.Wu, C.D.Hsiao, E.Breslow, B.C.Wang
Molecule: Oxytocin bound to Neurophysin II.
Organism_scientific: Bos Taurus
Method: X-Ray Diffraction. Resolution 2.8 �.

Oxytocin is a hormone that induces labor in pregnant woman and stimulates milk production in nursing mothers. Two oxytocin molecules are shown here as they are bound to a protein. Once you have identified the oxytocin molecules, zoom in, change to ball & stick and CPK color and find the -S-S- bridge.