Introduction
Proenkephalin (PENK), formerly known as proenkephalin A (since
proenkephalin B was renamed
prodynorphin Prodynorphin, also known as proenkephalin B, is an opioid polypeptide hormone involved with chemical signal transduction and cell communication. The gene for prodynorphin is expressed in the endometrium and the striatum, and its gene map locus is 20 ...
), is an
endogenous opioid
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
polypeptide hormone
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are require ...
which, via
proteolyic
Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, ...
cleavage, produces the
enkephalin
An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephali ...
peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
...
s
etnkephalin, and to a lesser extent,
eunkephalin.
Upon cleavage, each proenkephalin peptide results in the generation of four copies of
etnkephalin, two extended copies of
etnkephalin, and one copy of
eunkephalin.
Contrarily,
eunkephalin] is predominantly synthesized from prodynorphin, which produces three copies of it per cleavage, and no copies of
etnkephalin. Other endogenous opioid peptides produced by proenkephalin include
adrenorphin
Adrenorphin, also sometimes referred to as metorphamide, is an endogenous, C-terminally amidated, opioid octapeptide (Tyr-Gly-Gly-Phe-Met-Arg-Arg-Val-NH2, YGGFMRRV-NH2) that is produced from proteolytic cleavage of proenkephalin A and is wid ...
,
,
,
,
,
,
,
and
peptide F.
Proenkephalin in human diseases
Proenkephalin is produced by the medium spiny neurons of the striatum which undergo neurodegeneration in early stages of Huntingtons disease (HD). PENK and related peptides
measured in cerebrospinal fluid are proposed as potential biomarkers of disease progression in HD.
See also
*
Prodynorphin Prodynorphin, also known as proenkephalin B, is an opioid polypeptide hormone involved with chemical signal transduction and cell communication. The gene for prodynorphin is expressed in the endometrium and the striatum, and its gene map locus is 20 ...
(Proenkephalin B)
*
Proopiomelanocortin
Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. POMC is synthesized in corticotrophs of the anterior pituitary from the 267-amino-acid-long polypeptide precursor pre-pro-opiomelanocortin (pre-POMC), by the ...
(POMC)
References
External links
*
{{Opioidergics
Opioids
Neuropeptides
Precursor proteins