Carboxypeptidase E hydrolyzes Insulin(57-89) to yield C-peptide (Insulin(57-87))

Stable Identifier
Reaction [transition]
Homo sapiens
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The exopeptidase Carboxypeptidase E (CPE, also called Carboxypeptidase H) successively cleaves the C terminal arginine 89 and lysine 88 from insulin(57-89) to yield C peptide, which is released in equimolar amounts with mature insulin by vesicle exocytosis. The biochemical details of this reaction have been worked out for the rat protein (Davidson & Hutton 1987) and studies of variant forms of the human protein suggest the same function for human CPE Chen et al. 2001). The reaction occurs in immature secretory granules (Orci et al. 1985).
Literature References
PubMed ID Title Journal Year
11462236 Missense polymorphism in the human carboxypeptidase E gene alters enzymatic activity

Glaser, B, Moore, KJ, Gross, DJ, Parker, A, Qian, Y, Chan, G, Permutt, MA, Duong, Q, Chen, H, Jawahar, S, Fricker, LD, Meyer, JM, Chayen, S

Hum Mutat 2001
2822027 The insulin-secretory-granule carboxypeptidase H. Purification and demonstration of involvement in proinsulin processing

Davidson, HW, Hutton, JC

Biochem. J. 1987
3896518 Direct identification of prohormone conversion site in insulin-secreting cells

Vassalli, JD, Madsen, O, Amherdt, M, Perrelet, A, Orci, L, Ravazzola, M

Cell 1985
Catalyst Activity

metallocarboxypeptidase activity of CPE:Zn2+ [secretory granule membrane]

Inferred From
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