Melanocortin 3 receptor (MC
3R) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
Function
This gene encodes MC
3R, a
G-protein coupled receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...
(GPCR) for
melanocyte-stimulating hormone
The melanocyte-stimulating hormones, known collectively as MSH, also known as melanotropins or intermedins, are a family of peptide hormones and neuropeptides consisting of α-melanocyte-stimulating hormone (α-MSH), β-melanocyte-stimulating ...
(MSH) and
adrenocorticotropic hormone
Adrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important c ...
(ACTH) that is expressed in the brain. This gene maps to the same region as the ''locus'' for benign neonatal epilepsy. Mice deficient for this gene have increased fat mass, reduced lean mass and decreased food intake, all suggesting a role for the receptor in the regulation of energy homeostasis.
''MC3R'' mutations has been linked to reduced growth rate during childhood and a delay in the age of
puberty
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a bo ...
onset.
Research
Studies performed by the Eunice Kennedy Shriver National Institute of Child Health and Human Developmen
(NICHD) found that two specific polymorphisms in the ''MC3R'' gene may be associated with pediatric obesity and greater body mass because of greater energy intake. Children who were homozygous for C17A + G241A consumed approximately 38% more than those who did not contain aforementioned polymorphisms. The study concluded that these genetic variants did not affect energy expenditure.
Ligands
*
Ac-Val-Gln-(pI)DPhe-DTic-NH2, first MC
3 selective agonist, 100x selectivity over MC
4.
*
Ac-Val-Gln-DBip-DTic-NH2, 140x selectivity over MC
4.
* Pyrrolidine bis-cyclic guanidines, non-peptide small molecule MC
3 agonists, good selectivity over MC
4 but not over MC
1 or MC
5.
*
SHU-9119, mixed MC
3/MC
4 antagonist.
See also
*
Melanocortin receptor
Melanocortin receptors are members of the rhodopsin family of 7-transmembrane G protein-coupled receptors.
There are five known members of the melanocortin receptor system each with differing specificities for melanocortins:
* . MC1R is associat ...
References
Further reading
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External links
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G protein-coupled receptors
Human proteins
{{transmembranereceptor-stub