Linked Life Data

3310184

Source:http://linkedlifedata.com/resource/pubmed/id/3310184

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6-7
pubmed:dateCreated
1987-11-12
pubmed:abstractText
Proopiomelanocortin (POMC) is a glycoprotein which serves as a multihormonal precursor for corticotropin (ACTH), lipotropins (beta and gamma-LPH), melanotropins (alpha, beta- and gamma-MSH) and endorphins (alpha-, beta- and gamma-endorphins). This precursor protein is primarily synthesized in corticotrophs of the anterior lobe and in melanotrophs of the intermediate lobe of the pituitary, as well as in other organs or tissues such as the genitourinary tract, the gastrointestinal tract and leukocytes. POMC is also present in the central nervous system (CNS) and numerous studies have been conducted to determine the localization, biosynthesis and functions of POMC-derived peptides. The identification of POMC-neuronal systems has been achieved by combining immuno histochemical studies, biochemical analysis, bioassays and radioimmunoassays. Three groups of perikarya containing various POMC-related peptides have been identified. One of these is located in the arcuate nucleus in the basal hypothalamus and projects towards the septum, thalamus and telencephalon. Some fibers originating from the arcuate nucleus terminate in the nucleus of the solitary tract in the brainstem where a second group of POMC-containing nerve cells are located. The latter innervates both the mesencephalon, the brainstem and the spinal cord. A third group of neurons, which contain alpha-MSH but not other POMC-derivates, has been identified in the zona incerta in the dorso-lateral hypothalamus. Processing of POMC in the cell bodies of the arcuate nucleus follows a similar pattern as in the pituitary intermediate lobe. Endopeptidases called "acid-thiol-arginyl-proteases" cleave the prohormone at paired basic amino acids. The basic residues remaining on the resulting peptides are subsequently eliminated by the joint action of the less specific B-type carboxypeptidases and B-type aminopeptidases. alpha-MSH and beta-endorphin are among the major end products. Enzymatic modifications including N-alpha-acetylation by opiomelanotropin-acetyltransferase (OMAT) and/or C-terminal amidation by peptidyl-glycine alpha-amidating monooxygenase (PAM) occur after proteolytic processing. However, the rate of acetylation observed in hypothalamic POMC neurons is much lower than in the melanotrophs of the pars intermedia. Acetylation of MSH and endorphin is crucial in determining the biological potency of these peptides. Desacetyl alpha-MSH is far less active than alpha-MSH (monoacetyl alpha-MSH), whereas acetylated beta-endorphin has no opiate activity. The mechanisms regulating the activity of POMC-containing neurons are still unknown.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:language
fre
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0035-3787
pubmed:author
pubmed:issnType
Print
pubmed:volume
143
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
471-89
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
[Pro-opiomelanocortin neuronal systems].
pubmed:affiliation
Groupe de Recherche en Endocrinologie Moléculaire, UA CNRS 650, Unité Alliée à l'INSERM, Faculté des Sciences, Université de Rouen, France.
pubmed:publicationType
Journal Article, English Abstract, Review