Heme biosynthesis (Drosophila melanogaster)

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HOMOLOGY MAPPprotoporphyrin IXprotoporphyrinogen IXporphobilinogencoproporphyrinogen IIIO23 porphobilinogens + H2O+Fe2+uroporphyrinogen IIIprotohemeBlack - reactantsrate limiting stepRed - side productshydroxymethylbilaneO2ALAS1CoAUpdodelta-aminolevulinateCG1885AlasCoproxPbgsferrochelatasel(3)02640succinyl-CoAPpoxCO22 H2O4 NH3H2O4 CO22 CO2H2O22 H+glycinedelta-aminolevulinate


Description

The enzymatic process that produces heme is properly called porphyrin synthesis, as all the intermediates are tetrapyrroles that are chemically classified are porphyrins. The process is highly conserved across biology. In humans, this pathway serves almost exclusively to form heme. In other species, it also produces similar substances such as cobalamin (vitamin B12).

The pathway is initiated by the synthesis of D-Aminolevulinic acid (dALA or δALA) from the amino acid glycine and succinyl-CoA from the citric acid cycle (Krebs cycle). The rate-limiting enzyme responsible for this reaction, ALA synthase, is strictly regulated by intracellular iron levels and heme concentration. A low-iron level, e.g., in iron deficiency, leads to decreased porphyrin synthesis, which prevents accumulation of the toxic intermediates. This mechanism is of therapeutic importance: infusion of heme arginate or hematin can abort attacks of porphyria in patients with an inborn error of metabolism of this process, by reducing transcription of ALA synthase.

The organs mainly involved in heme synthesis are the liver and the bone marrow, although every cell requires heme to function properly. Heme is seen as an intermediate molecule in catabolism of haemoglobin in the process of bilirubin metabolism.

Source: WIkipedia

http://en.wikipedia.org/wiki/Heme

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History

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CompareRevisionActionTimeUserComment
116923view09:42, 16 May 2021EweitzModified title
91030view07:02, 23 December 2016EgonwAdded missing metabolite IDs.
89928view13:35, 6 October 2016Mkutmonfixed xref
89922view13:34, 6 October 2016MkutmonModified description
71007view18:48, 22 September 2013EgonwConverted several labels to Metabolite DataNodes.
70237view21:25, 15 July 2013MaintBotupdated to 2013 schema
67335view10:39, 26 June 2013Christine ChichesterOntology Term : 'heme biosynthetic pathway' added !
40886view22:34, 1 March 2011MaintBotRemoved redundant pathway information and comments
35289view22:51, 11 February 2010Mills42Modified description
21245view11:31, 14 November 2008MaintBot[[Pathway:Drosophila melanogaster:Heme Biosynthesis]] moved to [[Pathway:WP269]]: Moved to stable identifier
8615view14:04, 7 January 2008MaintBotAdded to category $category
8613view14:04, 7 January 2008KdahlquistUploaded new pathway

External references

DataNodes

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NameTypeDatabase referenceComment
2 CO2Metabolite
2 H+Metabolite
2 H2OMetabolite
4 CO2Metabolite
4 NH3Metabolite
ALAS1GeneProduct (Entrez Gene)
AlasGeneProduct37815 (Entrez Gene)
CG1885GeneProduct31817 (Entrez Gene)
CO2Metabolite
CoAMetabolite
CoproxGeneProduct44701 (Entrez Gene)
H2OMetabolite
H2O2Metabolite
PbgsGeneProduct39402 (Entrez Gene)
PpoxGeneProduct42939 (Entrez Gene)
UpdoGeneProduct35986 (Entrez Gene)
delta-aminolevulinateMetabolite
ferrochelataseGeneProduct43757 (Entrez Gene)
glycineMetabolite
l(3)02640GeneProduct46140 (Entrez Gene)
succinyl-CoAMetabolite

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