Differential rates of conversion of rat proinsulins I and II. Evidence for slow cleavage at the B-chain/C-peptide junction of proinsulin II.
Rat proinsulin I is converted into insulin more rapidly than is proinsulin II. To study this further, rat islets were labelled (10 min) and conversion kinetics of the labelled proinsulins were monitored during a 120 min chase. Proinsulins, conversion intermediates and both insulins were separated by h.p.l.c. The accumulation of des-64,65-(split proinsulin II) during the chase suggests that the B-chain/C-peptide junction of proinsulin II is cleaved more slowly than the equivalent site on proinsulin I. This accounts for the differential kinetics of conversion of proinsulins I and II, and is presumed to be caused by one (or more) of the amino acid replacements which distinguish the two proinsulins.
Sizonenko
S V
SV
Laboratories de Recherche Louis Jeantet, Centre Médical Universitaire, Geneva, Switzerland.
Halban
P A
PA
D000818:Animals; D002096:C-Peptide / Q000378:metabolism*; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011384:Proinsulin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014357:Trypsin / Q000378:metabolism
D002096:C-Peptide; D007328:Insulin; D011384:Proinsulin; D002268:Carboxypeptidases; D043424:Carboxypeptidase B; D014357:Trypsin