Proglucagon

{{Short description|Protein that is a precursor of glucagon}}

{{Infobox gene}}

Proglucagon is a protein that is a precursor of glucagon and several other components. It is cleaved from preproglucagon.

Proglucagon is generated in the alpha cells of the pancreas and in the intestinal L cells in the distal ileum and colon.

Preproglucagon in humans is encoded by the GCG gene and is composed of 180 amino-acid residues.{{cite journal | vauthors = Schroeder WT, Lopez LC, Harper ME, Saunders GF | title = Localization of the human glucagon gene (GCG) to chromosome segment 2q36–37 | journal = Cytogenetics and Cell Genetics | volume = 38 | issue = 1 | pages = 76–79 | year = 1984 | pmid = 6546710 | doi = 10.1159/000132034 }}{{cite journal | vauthors = White JW, Saunders GF | title = Structure of the human glucagon gene | journal = Nucleic Acids Research | volume = 14 | issue = 12 | pages = 4719–4730 | date = June 1986 | pmid = 3725587 | pmc = 311486 | doi = 10.1093/nar/14.12.4719 }}

More specifically, preproglucagon is cleaved into the following components in different organs:

• Signal peptide (1-20) – removed from preproglucagon to form proglucagon (21-180)
• Glicentin (21–89)
• Glicentin-related pancreatic polypeptide (GRPP, 21-50)
• Oxyntomodulin (OXY or OXM, 53–89)
• Glucagon (53–81)
• Glucagon-like peptide 1 (GLP-1, 92–128) – first seven residues further cleaved
• Glucagon-like peptide 2 (GLP-2, 146–178)

Proglucagon itself is a protein with three repeats of slightly different secretin family hormones to be cleaved to form mature hormones.{{cite journal | vauthors = Pollock HG, Hamilton JW, Rouse JB, Ebner KE, Rawitch AB | title = Isolation of peptide hormones from the pancreas of the bullfrog (Rana catesbeiana). Amino acid sequences of pancreatic polypeptide, oxyntomodulin, and two glucagon-like peptides | journal = The Journal of Biological Chemistry | volume = 263 | issue = 20 | pages = 9746–9751 | date = July 1988 | pmid = 3260236 | doi = 10.1016/S0021-9258(19)81581-8 | doi-access = free }}