Slow cleavage at the proinsulin B-chain/connecting peptide junction associated with low levels of endoprotease PC1/3 in transformed beta cells.
Conversion of rat proinsulins I and II was slower in transformed INS cells than in primary (islet) beta cells, with accumulation of des-64,65 but no detectable des-31,32-split proinsulin, indicating slow cleavage at the B-chain/connecting peptide (C-peptide) junction. Western blot analysis showed lower levels of the endoprotease PC1/3 in INS cells than in beta cells, as well as a 4-fold reduction in the ratio of PC1/3 to PC2, thus supporting the hypothesis that PC1/3 is the endoprotease responsible for cleavage at the B-chain/C-peptide junction.
Laboratoires de Recherche Louis Jeantet, University of Geneva Medical Center, Switzerland.
M
M
Neerman-Arbez
S V
SV
Sizonenko
P A
PA
Halban
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D002096:C-Peptide / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism; D007700:Kinetics; D008297:Male; D043484:Proprotein Convertases; D051381:Rats; D017207:Rats, Sprague-Dawley
D002096:C-Peptide; D043484:Proprotein Convertases; D016282:Aspartic Acid Endopeptidases