In vitro conversion of proinsulin to insulin by cathepsin B and role of C-peptide.
Cathepsin B, purified from isolated islets of Langerhans, when incubated with proinsulin under in vitro conditions could convert proinsulin to insulin and C-peptide, releasing free arginine and lysine. When C-peptide, prepared from rat pancreas, was added to the incubation system consisting of proinsulin and cathepsin B, it completely inhibited the conversion of proinsulin to insulin.
D000818:Animals; D002096:C-Peptide / Q000378:metabolism* / Q000494:pharmacology; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007328:Insulin / Q000096:biosynthesis*; D007515:Islets of Langerhans / Q000378:metabolism*; D008247:Lysosomes / Q000201:enzymology; D010455:Peptides / Q000378:metabolism*; D011384:Proinsulin / Q000378:metabolism*; D051381:Rats
D002096:C-Peptide; D007328:Insulin; D010455:Peptides; D011384:Proinsulin; D002403:Cathepsins