Calcyclin, a Calcium-Binding Protein, which Regulates Insulin Secretion from the Permeabilized Pancreatic β-Cell
- 124 Downloads
Although it is widely accepted that an increase in intracellular Ca2+ is a crucial event in the stimulus-secretion coupling in the pancreatic β-cell , we have limited knowledge on the later steps in the signal transduction pathway. Calcium binding proteins are considered to be involved in the control of Ca2+-dependent cellular functions including hormone release . Various types of calcium-binding proteins such as calmodulin, calbindin and S-100b protein are identified in the islet cells biochemically or immunohistochemically [3,4]. Calmodulin, the best characterized calcium binding protein, was demonstrated to exist in the pancreatic islet cells by Sugden et al . The pancreatic β-cell possesses the kinase activity which is dependent on Ca2+/calmodulin . Involvement of calmodulin and calmodulin-dependent protein kinases in insulin release has been suggested mainly based on the inhibitory effect of calmodulin antagonists on the release [7,8,9], albeit there is the argument against this idea .
KeywordsPancreatic Islet Insulin Release Calcium Binding Protein Pancreatic Islet Cell Rabbit Lung
Unable to display preview. Download preview PDF.
- 7.H. Niki, A. Niki and H. Hidaka, Effects of a new calmodulin inhibitor (W-7) on insulin release and biosynthesis. Biomed. Res. 2:413 (1981).Google Scholar
- 15.H. Todoroki, R. Kobayashi, M. Watanabe, H. Minami and H. Hidaka, Purification, characterization and partial sequence analysis of a newly identified EF-hand type 13-kDa Ca2+-binding protein from smooth muscle and non-smooth muscle tissues. J.Biol.Chem. 266:18668 (1992).Google Scholar
- 17.T. Tamagawa, A. Niki, H. Niki and I. Niki, Regulation of insulin release independent of changes of changes of cytosolic Ca2+ concentration, in: “Biophysics of the pancreatic B-cell.” (I. Atwater, E. Rojas and Soria B. eds.), Plenum Pub. Co. New York, pp293 (1987).Google Scholar
- 18.P.M. Jones, and S.L. Howell, Insulin secretion studied in islet permeabilized by high voltage discharge, in: Biophysics of the pancreatic B-cell (I. Atwater, E. Rojas and Soria, eds.) Plenum Pub. Co. New York. pp. 279 (1987).Google Scholar
- 19.H. Tokumitu, A. Mizutani, H. Minami, R. Kobayashi and H. Hidaka, A calcyclin-associated protein is a newly identified member of the Ca27phospholipid-binding proteins, annexin family. J. Biol. Chem. 267: 8919 (1992).Google Scholar