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Selective localization of calpain I (the low‐Ca 2+ ‐requiring form of Ca 2+ ‐dependent cysteine proteinase) in B‐cells of human pancreatic islets
Author(s) -
Kitahara Aiko,
Ohtsuki Hitoshi,
Kirihata Yoshiko,
Yamagata Yoko,
Takano Emiko,
Kannagi Reiji,
Murachi Takashi
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80666-9
Subject(s) - calpain , cysteine , pancreatic islets , chemistry , microbiology and biotechnology , biochemistry , islet , biology , endocrinology , enzyme , insulin
An immunohistochemical study was performed to localize two distinct Ca 2+ ‐proteases (low‐Ca 2+ ‐requiring calpain I and high‐Ca 2+ ‐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 Ca 2+ ‐dependent proteolysis in B‐cells can be triggered by a small rise of the intracellular Ca 2+ concentration without serious interference by the endogenous inhibitor.