title: Adenylate cyclase activation and competitive binding with renal tissue using synthetic eel calcitonin analog and its fragments.
abstract: The structure-function relationship of calcitonin (CT) was investigated using a synthetic eel CT (E-CT) analog and its fragments. Adenylate cyclase activation and competitive binding to rat renal receptors were used as parameters of function. [Asu1,7]E-CT analog, synthesized by replacing the S-S bond of Cys1-Cys7 in the natural hormone with ethylene linkage of 1-amino suberic acid (Asu), and E-CT fragment 11-32 had about 1/5th and 1/50th the potencies of synthetic E-CT, respectively, in both adenylate cyclase activation and competitive inhibition of 125I-labeled [Asu1,7]iodo-E-CT binding on rat renal plasma membranes. The minimal chain length required to activate adenylate cyclase in rat renal plasma membranes was between 12-18 amino acids, and the minimal chain length required to affect the CT receptor binding was between 6-12 amino acids, near the C-terminus. Fragments, including the C-terminus, show a disproportionate and potent inhibition of the binding compared with the potency required for adenylate cyclase activation. Thus, the amino acid sequence near the C-terminus probably plays an important role in the binding of CT to the receptor. (Endocrinology 108: 698, 1981.)
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002116:Calcitonin / Q000031:analogs & derivatives / Q000032:analysis / Q000502:physiology*; D004524:Eels / Q000502:physiology; D004789:Enzyme Activation; D006728:Hormones / Q000032:analysis / Q000378:metabolism; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism*; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D006728:Hormones; D002116:Calcitonin; D000262:Adenylyl Cyclases