title: Selective localization of calpain I (the low-Ca2+-requiring form of Ca2+-dependent cysteine proteinase) in B-cells of human pancreatic islets.
abstract: An immunohistochemical study was performed to localize two distinct Ca2+-proteases (low-Ca2+-requiring calpain I and high-Ca2+-requiring calpain II) and their specific inhibitor (calpastatin) in human pancreas using the respective monospecific antibodies. Strongly positive staining by anti-calpain I antibody was found in pancreatic islets, specifically in B-cells, whereas the exocrine pancreatic tissue showed essentially no positive immunostaining. No such specific staining was found with anti-calpain II antibodies or anti-calpastatin antibodies. The results suggest that the Ca2+-dependent proteolysis in B-cells can be triggered by a small rise of the intracellular Ca2+ concentration without serious interference by the endogenous inhibitor.
authors.forename: A
authors.initials: A
authors.lastname: Kitahara
authors.forename: H
authors.initials: H
authors.lastname: Ohtsuki
authors.forename: Y
authors.initials: Y
authors.lastname: Kirihata
authors.forename: Y
authors.initials: Y
authors.lastname: Yamagata
authors.forename: E
authors.initials: E
authors.lastname: Takano
authors.forename: R
authors.initials: R
authors.lastname: Kannagi
authors.forename: T
authors.initials: T
authors.lastname: Murachi
mesh_terms: D002118:Calcium / Q000502:physiology; D002154:Calpain; D010450:Endopeptidases / Q000032:analysis* / Q000276:immunology; D006651:Histocytochemistry; D006801:Humans; D007515:Islets of Langerhans / Q000201:enzymology*; D011493:Protein Kinase C; D011494:Protein Kinases / Q000032:analysis
chemical_list: D011494:Protein Kinases; D011493:Protein Kinase C; D010450:Endopeptidases; D002154:Calpain; D002118:Calcium