Structural and functional organization of some pituitary protein hormones.

Some recent observations on the interrelation between structural and functional organization of some anterior pituitary hormones (corticotropin, beta-lipotropin, prolactin and somatotropin) made in this Institute are reviewed. The primary structure and interspecies differences of these hormones are discussed and a mathematical method of comparative analysis of the homologous amino acid sequences, which has been previously developed, is presented. A hypothesis has been raised that some sequences of the amino acid chains are closely related to the nature of biological effect of the appropriate protein hormone, while some other parts of the molecular are responsible predominantly for a contact with a specific receptor and several experimental data are presented which seem to be in agreement with such a view. This may be also supported by the observations that the lipolytic effect of somatotropin may be blocked by proteinase inhibitors (trasylol and methylamine) which shows that such an action presumably takes place only after a cleavage of its molecule by proteolytic enzymes into smaller fragments.