Hydroxycarboxylic acid receptor 3 (HCA₃), also known as niacin receptor 2 (NIACR2) and GPR109B, 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 ...

which in humans is encoded by the ''HCAR3''

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 ...

. HCA₃, like the other

hydroxycarboxylic acid receptor The hydroxycarboxylic acid receptor (abbreviated HCA receptor and HCAR) family includes the following human proteins: * Hydroxycarboxylic acid receptor 1 Hydroxycarboxylic acid receptor 1 (HCA1), formerly known as G protein-coupled receptor 81 (G ...

s HCA₁ and HCA₂, is 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). The primary endogenous

agonists An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agon ...

of HCA₃ are 3-hydroxyoctanoic acid and

kynurenic acid Kynurenic acid (KYNA or KYN) is a product of the normal metabolism of amino acid -tryptophan. It has been shown that kynurenic acid possesses neuroactive activity. It acts as an antiexcitotoxic and anticonvulsant, most likely through acting as an ...

. HCA₃ is also a low-affinity

biomolecular target A biological target is anything within a living organism to which some other entity (like an endogenous ligand or a drug) is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets ...

for

niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...

(aka nicotinic acid).

References

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Further reading