Proenkephalin
Protein-coding gene in the species Homo sapiens
From Wikipedia, the free encyclopedia
Proenkephalin (PENK), formerly known as proenkephalin A (since proenkephalin B was renamed prodynorphin), is an endogenous opioid polypeptide hormone which, via proteolyic cleavage, produces the enkephalin peptides met-enkephalin, and to a lesser extent, leu-enkephalin.[5] Upon cleavage, each proenkephalin peptide results in the generation of four copies of Met-enkephalin, two extended copies of met-enkephalin, and one copy of leu-enkephalin.[5] Contrarily, Leu-enkephalin is predominantly synthesized from prodynorphin, which produces three copies of it per cleavage, and no copies of Met-enkephalin. Other endogenous opioid peptides produced by proenkephalin include adrenorphin,[6] amidorphin,[7] BAM-18,[8] BAM-20P,[9] BAM-22P,[9] peptide B,[10] peptide E,[11] and peptide F.[12]
The following table lists the peptides that are derived from cleavage of the proenkephalin protein.[13]
| Peptide | Alternative Names | Amino acid positions |
|---|---|---|
| Met-enkephalin | Opioid growth factor (OGF) | 107–111 |
| PENK(114–133) | Neuropeptide E; ENK-20 | 114–133 |
| Leu-enkephalin | — | 150–154 |
| Met-enkephalin-Arg-Phe | MERF; Neuropeptide AF | 186–191 |
| Met-enkephalin-Arg-Gly-Leu | MERGL; Neuropeptide AM | 218–223 |
| PENK(237–258) | Neuropeptide F | 237–258 |
Clinical significance
Proenkephalin is produced by the medium spiny neurons of the striatum which undergo neurodegeneration in early stages of Huntington's disease (HD). PENK[14] and related peptides[15][16] measured in cerebrospinal fluid are proposed as potential biomarkers of disease progression in HD. Furthermore, PENK has been found associated with acute kidney injury[17] and glomerular filtration rate in steady-state and critically ill patients.[18][19]
See also
- Prodynorphin (Proenkephalin B)
- Proopiomelanocortin (POMC)