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Mastoparan, a peptide toxin from wasp venom, stimulates glycogenolysis mediated by an increase of the cytosolic free Ca 2+ concentration but not by an increase of cAMP in rat hepatocytes
Author(s) -
Tohkin Masahiro,
Yagami Tatsurou,
Matsubara Takashi
Publication year - 1990
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(90)80098-4
Subject(s) - mastoparan , extracellular , glycogenolysis , cytosol , intracellular , chemistry , inositol , endocrinology , biochemistry , medicine , venom , egta , biology , calcium , g protein , signal transduction , enzyme , receptor , metabolism , organic chemistry
A wasp venom, mastoparan, rapidly increased the cytosolic free Ca 2+ concentration ([Ca 2+ ] i ) and activated phosphorylase in rat hepatocytes in a concentration‐dependent manner. Mastoparan could increase [Ca 2+ ] i even in the absence of extracellular Ca 2+ , but a larger increase was observed in the presence of extracellular Ca 2+ . Thus, mastoparan mobilized Ca 2+ from intracellular and extracellular Ca 2+ stores. It also activated inositol triphosphate (IP 3 ) accumulation, but did not stimulate cAMP production. From these results, we conclude that mastoparan activates rat hepatic glycogenolysis mediated by the accumulation of IP 3 , which causes an increase of [Ca 2+ ] i but not that mediated by cAMP.