(''E'')-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP or HMB-PP) is an intermediate of the MEP
pathway
Pathway or pathways may refer to:
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(non-mevalonate pathway) of isoprenoid biosynthesis.
The enzyme
HMB-PP synthase (GcpE, IspG) catalyzes the conversion of
2-''C''-methyl-D-erythritol 2,4-cyclodiphosphate (MEcPP) into HMB-PP. HMB-PP is then converted further to
isopentenyl pyrophosphate
Isopentenyl pyrophosphate (IPP, isopentenyl diphosphate, or IDP) is an isoprenoid precursor. IPP is an intermediate in the classical, HMG-CoA reductase pathway (commonly called the mevalonate pathway) and in the ''non-mevalonate'' MEP pathway of i ...
(IPP) and
dimethylallyl pyrophosphate
Dimethylallyl pyrophosphate (DMAPP; or alternatively, dimethylallyl diphosphate (DMADP); also isoprenyl pyrophosphate) is an isoprenoid precursor. It is a product of both the mevalonate pathway and the MEP pathway of isoprenoid precursor biosynt ...
(DMAPP) by
HMB-PP reductase (LytB, IspH).
HMB-PP is an essential metabolite in most pathogenic bacteria including ''
Mycobacterium tuberculosis'' as well as in
malaria
Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or deat ...
parasites, but is absent from the human host.
HMB-PP is the physiological activator ("
phosphoantigen") for human
Vγ9/Vδ2 T cells, the major
γδ T cell
Gamma delta T cells (γδ T cells) are T cells that have a γδ T-cell receptor (TCR) on their surface. Most T cells are αβ (alpha beta) T cells with TCR composed of two glycoprotein chains called α (alpha) and β (beta) TCR chains. In contrast ...
population in peripheral blood. With a bioactivity of 0.1 nM it is 10,000-10,000,000 times more potent than any other natural compound, such as
IPP or alkyl amines. HMB-PP functions in this capacity by binding the B30.2 domain of
BTN3A1
Butyrophilin subfamily 3 member A1 is a protein that in humans is encoded by the ''BTN3A1'' gene.
References
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References
External links
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{{DEFAULTSORT:Hydroxymethylbutenyl Pyrophosphate
Biomolecules
Metabolism
Organophosphates
Hemiterpenes