The insulin and glucagon degrading proteinase of rat liver. Separation of the proteinase from the thiol-proteindisulfide oxidoreductases.
Insulin degrading enzymes of rat liver cytosol, the so-called insulin and glucagon degrading proteinase (IGP, EC 3.4.23.5), and two forms of the insulin degrading thiol-protein-disulfide oxidoreductase/isomerase (glutathione-insulin transhydrogenase, TPO, EC 1.8.4.2/5.3.4.1) were separated from each other and partially purified on DEAE-Sephadex. The highly purified proteinase was obtained by polyacrylamide gel electrophoresis of the DEAE-Sephadex-purified enzyme fraction and was used to produce monospecific antibodies to the IGP in rabbits. Strong evidence is given that the insulin and glucagon degrading proteinase is an autonomous enzyme existing in addition to the TPO forms in the cytosol of the liver. Combined action of the proteinase and the TPO system on radioiodinated insulin under various conditions in vitro revealed an independent and non-sequential degradation of insulin by these two enzyme systems.
D000818:Animals; D000906:Antibodies; D002402:Cathepsin D; D002403:Cathepsins / Q000276:immunology / Q000302:isolation & purification*; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005934:Glucagon / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D010088:Oxidoreductases / Q000302:isolation & purification*; D011490:Protein Disulfide Reductase (Glutathione) / Q000302:isolation & purification*; D051381:Rats
D000906:Antibodies; D007328:Insulin; D005934:Glucagon; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); D002403:Cathepsins; D002402:Cathepsin D