Metabotropic glutamate receptor 4 is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the GRM4 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

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Together with GRM6, GRM7 and GRM8 it belongs to group III of the metabotropic glutamate receptor

Metabotropic glutamate receptor

The metabotropic glutamate receptors, or mGluRs, are a type of glutamate receptor that are active through an indirect metabotropic process. They are members of the group C family of G-protein-coupled receptors, or GPCRs...

 family. Group III receptors are linked to the inhibition of the cyclic AMP cascade.
Activation of GRM4 has potential therapeutic benefits in the treatment of parkinson's disease

Parkinson's disease

Parkinson's disease is a degenerative disorder of the central nervous system...

. "Taste-GRM4" is involved in the perception of umami

Umami

Umami , popularly referred to as savoriness, is one of the five basic tastes together with sweet, sour, bitter, and salty.-Etymology:Umami is a loanword from the Japanese meaning "pleasant savory taste". This particular writing was chosen by Professor Kikunae Ikeda from umai "delicious" and mi ...

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Positive allosteric modulators (PAMs)

• Tricyclic thiazolopyrazole derivative 22a: EC₅₀ = 9 nM, E_max = 120%
• ML-128: EC₅₀ = 240 nM, E_max = 182%
• VU-001171: EC₅₀ = 650 nM, E_max = 141%, 36-fold shift
• VU-0155041: subtype-selective PAM, intrinsic allosteric agonist activity, robust in-vivo activity
• PHCCC
  PHCCC
  PHCCC is a research drug which acts as a glutamate receptor ligand, particularly being a positive allosteric modulator at the mGluR4 subtype, as well as an agonist at mGluR6. It has anxiolytic effects in animal studies. PHCCC and similar drugs have been suggested as novel treatments for Parkinson's...
  
  : PAM of mGluR4, negative allosteric modulator of mGluR1, direct agonist at mGluR6

Further reading