Lactic acid is an organic acid. It has a molecular formula CH3CH(OH)COOH. It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as natural sources. Lactic acid is an alpha-hydroxy acid (AHA) due to the presence of a hydroxyl group adjacent to the carboxyl group. It is used as a synthetic intermediate in many organic synthesis industries and in various biochemical industries. The conjugate base of lactic acid is called lactate.
Butyric acid (from Ancient Greek: βούτῡρον, meaning "butter"), also known under the systematic name butanoic acid, is a straight-chain alkyl carboxylic acid with the chemical formula CH3CH2CH2CO2H. It is an oily, colorless liquid with an unpleasant odor. Isobutyric acid (2-methylpropanoic acid) is an isomer. Salts and esters of butyric acid are known as butyrates or butanoates. The acid does not occur widely in nature, but its esters are widespread. It is a common industrial chemical and an important component in the mammalian gut.
In biochemistry, an orphan receptor is a protein that has a similar structure to other identified receptors but whose endogenous ligand has not yet been identified. If a ligand for an orphan receptor is later discovered, the receptor is referred to as an "adopted orphan". Conversely, the term orphan ligand refers to a biological ligand whose cognate receptor has not yet been identified.
β-Hydroxybutyric acid, also known as 3-hydroxybutyric acid or BHB, is an organic compound and a beta hydroxy acid with the chemical formula CH3CH(OH)CH2CO2H; its conjugate base is β-hydroxybutyrate, also known as 3-hydroxybutyrate. β-Hydroxybutyric acid is a chiral compound with two enantiomers: D-β-hydroxybutyric acid and L-β-hydroxybutyric acid. Its oxidized and polymeric derivatives occur widely in nature. In humans, D-β-hydroxybutyric acid is one of two primary endogenous agonists of hydroxycarboxylic acid receptor 2 (HCA2), a Gi/o-coupled G protein-coupled receptor (GPCR).
Most of the eicosanoid receptors are integral membrane protein G protein-coupled receptors (GPCRs) that bind and respond to eicosanoid signaling molecules. Eicosanoids are rapidly metabolized to inactive products and therefore are short-lived. Accordingly, the eicosanoid-receptor interaction is typically limited to a local interaction: cells, upon stimulation, metabolize arachidonic acid to an eicosanoid which then binds cognate receptors on either its parent cell or on nearby cells to trigger functional responses within a restricted tissue area, e.g. an inflammatory response to an invading pathogen. In some cases, however, the synthesized eicosanoid travels through the blood to trigger systemic or coordinated tissue responses, e.g. prostaglandin (PG) E2 released locally travels to the hypothalamus to trigger a febrile reaction. An example of a non-GPCR receptor that binds many eicosanoids is the PPAR-γ nuclear receptor.
G protein-coupled estrogen receptor 1 (GPER), also known as G protein-coupled receptor 30 (GPR30), is a protein that in humans is encoded by the GPER gene. GPER binds to and is activated by the female sex hormone estradiol and is responsible for some of the rapid effects that estradiol has on cells.
G protein-coupled receptor 35 also known as GPR35 is a G protein-coupled receptor which in humans is encoded by the GPR35 gene. Heightened expression of GPR35 is found in immune and gastrointestinal tissues, including the crypts of Lieberkühn.
Uracil nucleotide/cysteinyl leukotriene receptor is a G protein-coupled receptor that in humans is encoded by the GPR17 gene located on chromosome 2 at position q21. The actual activating ligands for and some functions of this receptor are disputed.
Putative G-protein coupled receptor 42 is a protein that in humans is encoded by the GPR42P gene.
Hydroxycarboxylic acid receptor 3 (HCA3), also known as niacin receptor 2 (NIACR2) and GPR109B, is a protein which in humans is encoded by the HCAR3 gene. HCA3, like the other hydroxycarboxylic acid receptors HCA1 and HCA2, is a Gi/o-coupled G protein-coupled receptor (GPCR). The primary endogenous agonists of HCA3 are 3-hydroxyoctanoic acid and kynurenic acid. HCA3 is also a low-affinity biomolecular target for niacin (aka nicotinic acid).
G protein-coupled receptor 55 also known as GPR55 is a G protein-coupled receptor that in humans is encoded by the GPR55 gene.
Hydroxycarboxylic acid receptor 1 (HCA1), formerly known as G protein-coupled receptor 81 (GPR81), is a protein that in humans is encoded by the HCAR1 gene. HCA1, like the other hydroxycarboxylic acid receptors HCA2 and HCA3, is a Gi/o-coupled G protein-coupled receptor (GPCR). The primary endogenous agonist of HCA1 is lactic acid (and its conjugate base, lactate).
2-Oxoglutarate receptor 1 (OXGR1), also known as cysteinyl leukotriene receptor E (CysLTE) and GPR99, is a protein that in humans is encoded by the OXGR1 gene. The Gene has recently been nominated as a receptor not only for 2-oxogluterate but also for the three cysteinyl leukotrienes (CysLTs), particularly leukotriene E4 (LTE4) and to far lesser extents LTC4 and LTE4. Recent studies implicate GPR99 as a cellular receptor which is activated by LTE4 thereby causing these cells to contribute to mediating various allergic and hypersensitivity responses.
G protein-coupled receptor 119 also known as GPR119 is a G protein-coupled receptor that in humans is encoded by the GPR119 gene.
Hydroxycarboxylic acid receptor 2 (HCA2), also known as niacin receptor 1 (NIACR1) and GPR109A, is a protein which in humans is encoded by the HCAR2 gene. HCA2, like the other hydroxycarboxylic acid receptors HCA1 and HCA3, is a Gi/o-coupled G protein-coupled receptor (GPCR). The primary endogenous agonists of HCA2 are D-β-hydroxybutyric acid and butyric acid (and their conjugate bases, β-hydroxybutyrate and butyrate). HCA2 is also a high-affinity biomolecular target for niacin (aka nicotinic acid).
Relaxin/insulin-like family peptide receptor 4, also known as RXFP4, is a human G-protein coupled receptor.
Oxoeicosanoid receptor 1 (OXER1) also known as G-protein coupled receptor 170 (GPR170) is a protein that in humans is encoded by the OXER1 gene located on human chromosome 2p21; it is the principal receptor for the 5-Hydroxyicosatetraenoic acid family of carboxy fatty acid metabolites derived from arachidonic acid. The receptor has also been termed hGPCR48, HGPCR48, and R527 but OXER1 is now its preferred designation. OXER1 is a G protein-coupled receptor (GPCR) that is structurally related to the hydroxy-carboxylic acid (HCA) family of G protein-coupled receptors whose three members are HCA1 (GPR81), HCA2, and HCA3 ; OXER1 has 30.3%, 30.7%, and 30.7% amino acid sequence identity with these GPCRs, respectively. It is also related to the recently defined receptor, GPR31, for the hydroxyl-carboxy fatty acid 12-HETE.
Apis cerana japonica is a subspecies of the eastern honey bee native to Japan. It is commonly known as the Japanese honey bee. This subspecies was determined, through an analysis of mitochondrial DNA, to have originally come from the Korean peninsula. They have been observed moving into urban areas in the absence of natural predators.
Cymbidium floribundum, the yellow margin orchid, golden leaf-edge orchid or golden-edged orchid, is a species of orchid.
The hydroxycarboxylic acid receptor (abbreviated HCA receptor and HCAR) family includes the following human proteins:
