The Somatotropin family is a protein family whose titular representative is somatotropin, also known as growth hormone, a hormone that plays an important role in growth control. Other members include choriomammotropin (lactogen), its placental analogue; prolactin, which promotes lactation in the mammary gland, and placental prolactin-related proteins; proliferin and proliferin related protein; and somatolactin from various fishes. The 3D structure of bovine somatotropin has been predicted using a combination of heuristics and energy minimisation.