Proglucagon

Proglucagon is a protein that is cleaved from preproglucagon. Preproglucagon in humans is encoded by the "GCG" gene.
Proglucagon is a precursor of glucagon, and several other components. It is generated in the alpha cells of the pancreas and in the intestinal L cells in the distal ileum and colon. It is also cleaved into the following components in different organs:
Proglucagon itself is a protein with three repeats of slightly different secretin family hormones to be cleaved to form mature hormones.