Interaction of Parathyroid Hormone with Membranes of Kidney Cortex: Degradation of the Hormone and Activation of Adenylate Cyclase1

作者：Luke L. H. Chu, Leonard Ralph Forte, Constantine S. Anast, David V. Cohn · 发表于：Endocrinology · 年份：1975 · DOI：10.1210/endo-97-4-1014 · 被引用次数：28 · 研究领域：Parathyroid Disorders and Treatments、Biomedical Research and Pathophysiology、Protein Kinase Regulation and GTPase Signaling

Plasma membranes prepared from rat renal cortex contain both a parathyroid hormone-sensitive adenylate cyclase and a potent proteolytic activity which degrades the hormone into peptide fragments. The degree and pattern of degradation was determined by subjecting incubation mixtures to gel filtration and ion exchange chromatography. Estimation of the degree of degradation by acid precipitation of the intact hormone was inadequate since metabolism of the hormone apparently generated acid-insoluble fragments. When parathyroid hormone was incubated with membrane fraction, the capacity of its stimulatory effect on adenylate cyclase decreased steadily. This decrease of PTH activitiy could be closely related to the degradation of intact hormone by the same membrane preparation. The adenylate cyclase and degradative activity appeared to exist in similar membrane structures since they could not be separated by centrifugation through sucrose density gradients. The degradation of the hormone could not be inhibited by Trasylol and pancreatic or soybean trypsin inhibitors and was only slightly inhibited by ribonuclease and benzamidine. Histone (1 mg per ml), on the other hand, was able to decrease the degradation of the hormone and prevent the loss of its activity. Radioimmunoassay of the incubation mixtures showed that the rapid degradation of both amino- and carboxy-terminal regions of the hormone was prevented by histone. The oxidized, inactive hormone was also degraded to the same ext...