LOCALIZATION OF GLUTATHIONE-INSULIN TRANSHYDROGENASE (PROTEIN-DISULFIDE INTERCHANGE ENZYME) IN PANCREAS USING IMMUNOCYTOCHEMISTRY, IMMUNODIFFUSION, AND ENZYMATIC-ACTIVITY ASSAY TECHNIQUES

  • 1 January 1985
    • journal article
    • research article
    • Vol. 39  (1) , 97-104
Abstract
The localization of the protein-disulfide interchange enzyme, glutathione-insulin transhydrogenase (GIT), in rat and mouse pancreas was studied by protein A-gold immunocytochemistry, immunodiffusion, and assay of enzymatic activity. Immunocytochemistry on tissue sections using antibody to GIT and protein A-gold complex indicated the presence of GIT in .alpha. and .beta. cells in islets as well as acinar cells. The .beta. cells in obese (ob/ob) hyperinsulinemic mice showed increased GIT immunoreactivity. In both .alpha. and .beta. cells, GIT immunoreactive sites were associated predominantly with secretory granules. In pancreas from rats injected with glibenclamide, the degranulated .beta. cells contained GIT immunoreactive sites on the cisternal surface of the rough endoplasmic reticulum (RER). In acinar cells, the RER, Golgi elements, condensing vacuoles, and zymogen granules possessed GIT immunoreactive sites as did mitochondria. Immunocytochemistry on sections of isolated subcellular fractions showed that GIT was associated with different membranes. The enzymatic activity of GIT was found in the following order: Golgi elements > mitochondria > microsomes > zymogen granules > cytosol. In Ouchterlony immunodiffusion tests, each subcellular fraction showed a precipitin band which was continuous with that of purified GIT, a result indicating the presence of immunologically identical GIT in all fractions.

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