title: Subcellular localization and partial characterization of insulin proteolytic activity in rat liver.
abstract: Using (A14-125I)-insulin as a tracer, insulin proteolytic activity in rat liver was found to be localized both to the cytosol and the endoplasmic reticulum. The membrane-associated activity was highly latent (70-80%). Both cytosolic and particulate activities had similar Km values and Mr of approx. 300 000 by gel filtration. Both were strongly inhibited by diamide (90%), but were unaffected by leupeptin or pepstatin. A comparison of the subcellular distributions with various 125I-isomers of insulin as tracers showed that both particulate and cytosolic activities were highest with (A14-125I)-insulin.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002850:Chromatography, Gel; D003600:Cytosol / Q000201:enzymology; D004721:Endoplasmic Reticulum / Q000201:enzymology; D007328:Insulin / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology; D008670:Metals / Q000494:pharmacology; D008862:Microsomes, Liver / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology*
chemical_list: D007328:Insulin; D008670:Metals; D011480:Protease Inhibitors