The Full Wiki

Proopiomelanocortin: Wikis

  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

edit
Proopiomelanocortin (adrenocorticotropin/ beta-lipotropin/ alpha-melanocyte stimulating hormone/ beta-melanocyte stimulating hormone/ beta-endorphin)
Identifiers
Symbols POMC; LPH; MSH; ACTH; CLIP; NPP; POC
External IDs OMIM176830 MGI97742 HomoloGene723 GeneCards: POMC Gene
RNA expression pattern
PBB GE POMC 205720 at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 5443 18976
Ensembl ENSG00000115138 ENSMUSG00000020660
UniProt P01189 P01193
RefSeq (mRNA) NM_000939 NM_008895
RefSeq (protein) NP_000930 NP_032921
Location (UCSC) Chr 2:
25.24 - 25.25 Mb
Chr 12:
3.95 - 3.96 Mb
PubMed search [1] [2]

Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues.

This gene encodes a polypeptide hormone precursor that undergoes extensive, tissue-specific, post-translational processing via cleavage by subtilisin-like enzymes known as prohormone convertases. There are eight potential cleavage sites within the polypeptide precursor and, depending on tissue type and the available convertases, processing may yield as many as ten biologically active peptides involved in diverse cellular functions. The encoded protein is synthesized mainly in corticotroph cells of the anterior pituitary where four cleavage sites are used; adrenocorticotrophin, essential for normal steroidogenesis and the maintenance of normal adrenal weight, and lipotropin beta are the major end products.

In other tissues, including the hypothalamus, placenta, and epithelium, all cleavage sites may be used, giving rise to peptides with roles in pain and energy homeostasis, melanocyte stimulation, and immune modulation. These include several distinct melanotropins, lipotropins, and endorphins that are contained within the adrenocorticotrophin and beta-lipotropin peptides.

Mutations in this gene have been associated with early onset obesity, adrenal insufficiency, and red hair pigmentation. Alternatively spliced transcript variants encoding the same protein have been described.[1]

Contents

Production

It is synthesized by:

Derivatives

proopiomelanocortin derivatives
POMC
     
γ-MSH ACTH β-lipotropin
         
  α-MSH CLIP γ-lipotropin β-endorphin
       
    β-MSH  

The large molecule of POMC is the source of several important biologically active substances. POMC can be cleaved enzymatically into the following peptides:

Although the N-terminal 5 amino acids of beta-endorphin are identical to the sequence of Met-enkephalin, it is not generally thought that beta-endorphin is converted into Met-enkephalin. Instead, Met-enkephalin is produced from its own precursor, proenkephalin.

The production of β-MSH occurs in humans but not in mice or rats due to the absence of the enzymatic processing site in the rodent POMC.

Function

Each of these peptides is packaged in large dense-core vesicles that are released from the cells by exocytosis in response to appropriate stimulation.:

Interactions

Proopiomelanocortin has been shown to interact with Melanocortin 4 receptor.[2][3]

See also

References

  1. ^ "Entrez Gene: POMC proopiomelanocortin (adrenocorticotropin/ beta-lipotropin/ alpha-melanocyte stimulating hormone/ beta-melanocyte stimulating hormone/ beta-endorphin)". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5443.  
  2. ^ Yang, Y K; Fong T M, Dickinson C J, Mao C, Li J Y, Tota M R, Mosley R, Van Der Ploeg L H, Gantz I (Dec. 2000). "Molecular determinants of ligand binding to the human melanocortin-4 receptor". Biochemistry (UNITED STATES) 39 (48): 14900–11. ISSN 0006-2960. PMID 11101306.  
  3. ^ Yang, Y K; Ollmann M M, Wilson B D, Dickinson C, Yamada T, Barsh G S, Gantz I (Mar. 1997). "Effects of recombinant agouti-signaling protein on melanocortin action". Mol. Endocrinol. (UNITED STATES) 11 (3): 274–80. ISSN 0888-8809. PMID 9058374.  

Further reading

External links


PD-icon.svg This article incorporates public domain material from websites or documents of the National Center for Biotechnology Information (Reference Sequence collection).








Got something to say? Make a comment.
Your name
Your email address
Message