Macrophage migration inhibitory factor (MIF) is a key regulatory cytokine within innate and adaptive immune responses, capable of promoting and modulating the magnitude of the response []. MIF is released from T-cells and macrophages, and acts within the neuroendocrine system. MIF is capable of tautomerase activity, although its biological function has not been fully characterised. It is induced by glucocorticoid and is capable of overriding the anti-inflammatory actions of glucocorticoid []. MIF regulates cytokine secretion and the expression of receptors involved in the immune response. It can be taken up into target cells in order to interact with intracellular signalling molecules, inhibiting p53 function, and/or activating components of the mitogen-activated protein kinase and Jun-activation domain-binding protein-1 (Jab-1) []. MIF has been linked to various inflammatory diseases, such as rheumatoid arthritis and atherosclerosis [].The MIF homologue D-dopachrome tautomerase () is involved in detoxification through the conversion of dopaminechrome (and possibly norepinephrinechrome), the toxic quinine product of the neurotransmitter dopamine (and norepinephrine), to an indole derivative that can serve as a precursor to neuromelanin [, ].The signature pattern for this entry is formed from a conserved region located in the central section.
Macrophage migration inhibitory factor (MIF) is a key regulatory cytokine within innate and adaptive immune responses, capable of promoting and modulating the magnitude of the response []. MIF is released from T-cells and macrophages, and acts within the neuroendocrine system. MIF is capable of tautomerase activity, although its biological function has not been fully characterised. It is induced by glucocorticoid and is capable of overriding the anti-inflammatory actions of glucocorticoid []. MIF regulates cytokine secretion and the expression of receptors involved in the immune response. It can be taken up into target cells in order to interact with intracellular signalling molecules, inhibiting p53 function, and/or activating components of the mitogen-activated protein kinase and Jun-activation domain-binding protein-1 (Jab-1) []. MIF has been linked to various inflammatory diseases, such as rheumatoid arthritis and atherosclerosis [].The MIF homologue D-dopachrome tautomerase () is involved in detoxification through the conversion of dopaminechrome (and possibly norepinephrinechrome), the toxic quinine product of the neurotransmitter dopamine (and norepinephrine), to an indole derivative that can serve as a precursor to neuromelanin [, ].
Hypoxia-inducible lipid droplet-associated protein (HILPDA), also known as hypoxia-inducible protein 2 (HIG2), increases intracellular lipid accumulation. It stimulates expression of cytokines including IL6, MIF and VEGFA. It also enhances cell growth and proliferation [, ]. Human HILPDA is highly expressed in renal cell carcinoma cells but barely detectable in adjacent normal kidney tissue. It is detected in some cervical and endometrial cancers [, , ].
Tautomerase superfamily members have a (beta-α-β)2 structure in two layers, and use a similar mechanism of action involving an amino-terminal proline as a general base in a ket-enol tautomerisation reaction []. Members of this superfamily include macrophage migration inhibitory factor (MIF) and related proteins such as D-dopachrome tautomerase; 4-oxalocrotonoate tautomerase and related enzymes such as trans-3-chloroacrylic acid dehalogenase; and 5-carboxymethyl-2-hydroxymuconate Delta-isomerase (CHMI).Macrophage migration inhibitory factor (MIF) is a key regulatory cytokine within innate and adaptive immune responses, capable of promoting and modulating the magnitude of the response []. MIF is released from T-cells and macrophages, and it can regulate cytokine secretion and the expression of receptors involved in the immune response. MIF has been linked to various inflammatory diseases, such as rheumatoid arthritis and atherosclerosis [].4-Oxalocrotonate tautomerase (4-OT) is a plasmid-encoded enzyme that catalyzes the isomerisation of beta,gamma-unsaturated enones to their alpha,beta-isomers. This enzyme is part of the plasmid-encoded catechol meta-fission pathway, which enables the bacteria to use various aromatic hydrocarbons as their sole sources of carbon and energy [].5-carboxymethyl-2-hydroxymuconate isomerase (CHMI) is a trimeric enzyme involved in the homoprotocatechuate pathway in Escherichia coli []. This enzyme catalyses the isomerisation of 5-carboxymethyl-2-hydroxymuconate (CHM) to 5-carboxymethyl-2-oxo-3-hexene-1,6-dioate (COHED).
