title: Relationships among several different non-homologous polypeptide hormones.
abstract: Several polypeptide hormones of apparently diverse structure and function have a number of similarities which suggest that there may be common features in their mechanism of action. These hormones are all composed of a single linear sequence of about 30 amino acids; their hydrophobic amino acids are regularly spaced at every third or fourth amino acid residue, allowing them to form amphipathic structures which can interact with phospholipids; a fragment at or near their N-terminus is required for biological activity. These hormones include glucagon, beta-endorphin, parathyroid hormone and calcitonin. A model is proposed in which all regions of the hormone bind to the receptor with comparable affinity except for a small segment which, when intact, triggers a conformational change in the receptor resulting in a further stabilization of the hormone-receptor complex. The activity of partial sequences and chemically modified forms of beta-endorphin, parathyroid hormone and glucagon are discussed in relation to this model.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002116:Calcitonin / Q000378:metabolism; D002417:Cattle; D004723:Endorphins / Q000378:metabolism; D005934:Glucagon / Q000378:metabolism; D006728:Hormones / Q000378:metabolism*; D008954:Models, Biological; D010281:Parathyroid Hormone / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D011487:Protein Conformation; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D006728:Hormones; D010281:Parathyroid Hormone; D010455:Peptides; D011956:Receptors, Cell Surface; D001615:beta-Endorphin; D002116:Calcitonin; D005934:Glucagon