Sequence Comparison of Human Pituitary Growth Hormone, Human Chorionic Somatomammotropin, and Ovine Pituitary Growth and Lactogenic Hormones

A comparison of the primary structure of human pituitary growth hormone, human chorionic somatomammotropin, ovine pituitary lactogenic hormone and ovine pituitary growth hormone indicates that all four molecules have evolved from a common ancestor. Ovine pituitary lactogenic hormone appears to have diverged from the other three proteins, and to have evolved independently over a relatively long period of time. Cross comparisons, intended to detect the presence of compact and mutually exclusive sequence segments that might be specifically correlated with the two types of biological activities displayed by these hormones, were unsuccessful.