The calcitonin receptor (CT) is a G protein-coupled receptor

G protein-coupled receptor

G protein-coupled receptors , also known as seven-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors , comprise a large protein family of transmembrane receptors that sense molecules outside the cell and activate inside signal...

 that binds the peptide hormone calcitonin

Calcitonin

Calcitonin is a 32-amino acid linear polypeptide hormone that is producedin humans primarily by the parafollicular cells of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium , opposing the effects of parathyroid hormone . Calcitonin has been found...

 and is involved in maintenance of calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 homeostasis

Homeostasis

Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...

, particularly with respect to bone formation and metabolism .

CT works by activating the G-proteins G_s

Gs alpha subunit

The Gs alpha subunit is a heterotrimeric G protein subunit that activates the cAMP-dependent pathway by activating adenylate cyclase.-Receptors:The G protein-coupled receptors that couple to this kind of G-protein include:...

 and G_q

Gq alpha subunit

Gq protein or Gq/11 is a heterotrimeric G protein subunit that activates phospholipase C . PLC in turn hydrolyzes Phosphatidylinositol 4,5-bisphosphate to diacyl glycerol and inositol triphosphate signal transduction pathway...

 often found on osteoclasts, on cells in the kidney, and on cells in a number of regions of the brain. . It may also affect the ovaries in women and the testes in men.

The function of the CT receptor protein is modified through its interaction with Receptor activity-modifying protein

Receptor activity-modifying protein

Receptor activity-modifying proteins are a class of protein which interact with and modulate the activities of several Class B G Protein-Coupled Receptors including the receptors for secretin, calcitonin , glucagon, and vasoactive intestinal peptide...

s (RAMPs), forming the multimeric amylin

Amylin

Amylin, or Islet Amyloid Polypeptide , is a 37-residue peptide hormone secreted by pancreatic β-cells at the same time as insulin .-Clinical significance:...

 receptors AMY₁ (CT + RAMP1), AMY₂ (CT + RAMP2), and AMY₃ (CT+ RAMP3) .

Interactions

Calcitonin receptor has been shown to interact

Protein-protein interaction

Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...

 with Apolipoprotein B

Apolipoprotein B

Apolipoprotein B is the primary apolipoprotein of low-density lipoproteins , which is responsible for carrying cholesterol to tissues. While it is unclear exactly what functional role APOB plays in LDL, it is the primary apolipoprotein component and is absolutely required for its formation...

 and LRP1

LRP1

Low density lipoprotein receptor-related protein 1 , also known as alpha-2-macroglobulin receptor , apolipoprotein E receptor or cluster of differentiation 91 , is a protein forming a receptor found in the plasma membrane of cells involved in receptor-mediated endocytosis...

.

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