Proglucagon is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that is a precursor of
glucagon
Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises the concentration of glucose and fatty acids in the bloodstream and is considered to be the main catabolic hormone of the body. It is also used as a Glucagon (medic ...
and several other components. It is cleaved from preproglucagon.
Proglucagon is generated in the
alpha cell
Alpha cells (α-cells) are endocrine cells that are found in the Islets of Langerhans in the pancreas. Alpha cells secrete the peptide hormone glucagon in order to increase glucose levels in the blood stream.
Discovery
Islets of Langerhans we ...
s of the
pancreas
The pancreas (plural pancreases, or pancreata) is an Organ (anatomy), organ of the Digestion, digestive system and endocrine system of vertebrates. In humans, it is located in the abdominal cavity, abdomen behind the stomach and functions as a ...
and in the intestinal
L cells in the distal
ileum
The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may ...
and
colon.
Preproglucagon in
human
Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...
s is encoded by the ''GCG''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
and is composed of 180
amino-acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
residues.
More specifically, preproglucagon is cleaved into the following components in different
organ
Organ and organs may refer to:
Biology
* Organ (biology), a group of tissues organized to serve a common function
* Organ system, a collection of organs that function together to carry out specific functions within the body.
Musical instruments
...
s:
*
Signal peptide
A signal peptide (sometimes referred to as signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequence or leader peptide) is a short peptide (usually 16–30 amino acids long) present at the ...
(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
Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises the concentration of glucose and fatty acids in the bloodstream and is considered to be the main catabolic hormone of the body. It is also used as a Glucagon (medic ...
(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.
References
Further reading
*
External links
*
*
*
*
{{Proglucagon
Pancreatic hormones
Precursor proteins