Receptor activity-modifying proteins (RAMPs) are a class of protein that interact with and modulate the activities of several Class B
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 ...
s including the receptors for
secretin
Secretin is a hormone that regulates water homeostasis throughout the body and influences the environment of the duodenum by regulating secretions in the stomach, pancreas, and liver. It is a peptide hormone produced in the S cells of the duoden ...
,
calcitonin
Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing ...
(CT),
glucagon
Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises concentration of glucose and fatty acids in the bloodstream, and is considered to be the main catabolic hormone of the body. It is also used as a medication to trea ...
, and
vasoactive intestinal peptide
Vasoactive intestinal peptide, also known as vasoactive intestinal polypeptide or VIP, is a peptide hormone that is vasoactive in the intestine. VIP is a peptide of 28 amino acid residues that belongs to a glucagon/secretin superfamily, the liga ...
(VIP).
There are three distinct types of RAMPs in mammals (though more in fish), designated
RAMP1
Receptor activity modifying protein 1 is a protein that in humans is encoded by the ''RAMP1'' gene.
The protein encoded by this gene is a member of the RAMP family of single-transmembrane-domain proteins, called receptor (calcitonin) activity mod ...
,
RAMP2, and
RAMP3, each encoded by a separate gene.
Function
Currently, the function of RAMPs is divided into classes of activities. When associated with the
Calcitonin receptor (CTR) or
Calcitonin receptor-like (CALCRL) (below), RAMPs can change the selectivity of the receptor for a specific hormone. In the cases of the other receptors mentioned, however, there is no evidence that they can do this, but instead function to regulate trafficking of receptors from the
ER /
golgi Golgi may refer to:
*Camillo Golgi (1843–1926), Italian physician and scientist after whom the following terms are named:
**Golgi apparatus (also called the Golgi body, Golgi complex, or dictyosome), an organelle in a eukaryotic cell
**Golgi tend ...
to the membrane. These functions appear to be ones where there is redundancy, as neither RAMP1 nor RAMP3
knockout mice
A knockout mouse, or knock-out mouse, is a genetically modified mouse (''Mus musculus'') in which researchers have inactivated, or " knocked out", an existing gene by replacing it or disrupting it with an artificial piece of DNA. They are importan ...
(KO) have grossly abnormal
phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological prop ...
s. The likelihood is that the phenotype of RAMP2 KO mice is more connected with the abolition of most
adrenomedullin
Adrenomedullin (ADM or AM) is a vasodilator peptide hormone of uncertain significance in human health and disease. It was initially isolated in 1993 from a pheochromocytoma, a tumor of the adrenal medulla: hence the name.
In humans ADM is enc ...
(AM) signalling than effects on trafficking of other receptors, as those mice are almost identical to AM KO mice and mice lacking the Calcitonin-like receptor which are unable to form either AM1 or AM-2 adrenomedullin receptors (CLR/RAMP2 and CLR/RAMP3 respectively).
Types
Association of RAMPs with either the
CT or
CALCRL proteins forms 6 different receptors from the calcitonin receptor family:
[*]
References
External links
*
*
Single-pass transmembrane proteins
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