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Title: Insulin-induced alterations in the lactoperoxidase-catalyzed radioiodination of membrane proteins of the toad bladder epithelium

Journal Article · · Endocrinology; (United States)

Insulin-stimulated sodium transport in the toad urinary bladder consists of two components, a brief element of rapid onset that is independent of protein synthesis, and a sustained increase, slower in onset, that is dependent upon RNA and protein synthesis. The mucosal epithelium of the toad bladder was labeled by lactoperoxidase-catalyzed radioiodination (125I) following 15 min and 3 h exposure to insulin. The membrane of ''mitochondria-rich'' and ''granular'' mucosal cells from these tissues were analyzed by electrophoresis in SDS-urea. Compared to untreated tissues, membranes of ''granular'' mucosal cells from tissues exposed to insulin for 15 min contained a band (Mr . 15,000) with significantly increased labeling. Bladders exposed to insulin for 3 h showed no consistent increase in labeling. These data suggest that there are differences in the conformation of apical membrane proteins during the two phases of hormone-induced sodium transport. The technique may also offer an opportunity to identify ''effector'' proteins mediating this and other insulin responses.

Research Organization:
Department of Physiology, Mount Sinai School of Medicine, New York
OSTI ID:
5551293
Journal Information:
Endocrinology; (United States), Vol. 109:5
Country of Publication:
United States
Language:
English

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