ALAD - Delta-aminolevulinic acid dehydratase - human protein (Function)
 
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ALAD »  Delta-aminolevulinic acid dehydratase   [ EC 4.2.1.24 ]  (ALADH)
 
Protein also known as:  Porphobilinogen synthase.
Gene name:  ALAD
Family name: ALADH
Entry whose protein(s) existence is based on evidence at protein level
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GENE REF ISO

Function

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Overview 
Catalyzes an early step in the biosynthesis of tetrapyrroles. Binds two molecules of 5-aminolevulinate per subunit, each at a distinct site, and catalyzes their condensation to form porphobilinogen.  
2
  • CuratedUniProtKB
GO molecular function 
Catalytic activitydefinition[GO:0003824]  
1
  • TASPINC
Identical protein bindingdefinition[GO:0042802]  
1
  • IPIUniProtKB
Lead ion bindingdefinition[GO:0032791]  
1
  • IDAUniProtKB
Porphobilinogen synthase activitydefinition[GO:0004655]  
1
  • IDAUniProtKB
Zinc ion bindingdefinition[GO:0008270]  
1
  • IDAUniProtKB
GO biological process 
Cellular response to interleukin-4definition[GO:0071353] silver  
  • IEAOrtholog Compara
Heme biosynthetic processdefinition[GO:0006783]  
1
  • IDAUniProtKB
Protein homooligomerizationdefinition[GO:0051260]  
1
  • IPIUniProtKB
Protoporphyrinogen IX biosynthetic processdefinition[GO:0006782]  
  • IEAUniPathway
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 4.2.1.24: 2 5-aminolevulinate porphobilinogen + 2 H(2)O.  
3
  • CuratedUniProtKB
It requires the following cofactor
Binds 8 zinc ions per octamer. Requires four zinc ions per octamer for full catalytic activity. Can bind up to 2 zinc ions per subunit.  
1
  • CuratedUniProtKB
It is regulated in the following manner
Can alternate between a fully active homooctamer and a low-activity homohexamer. A bound magnesium ion may promote the assembly of the fully active homooctamer. The magnesium-binding site is absent in the low-activity homohexamer. Inhibited by compounds that favor the hexameric state. Inhibited by divalent lead ions. The lead ions partially displace the zinc cofactor.  
3
  • CuratedUniProtKB
Pathways 
This protein is involved in the following pathway
According to KEGG, this protein belongs to the following pathways:
Metabolic pathways  hsa01100+210  
Porphyrin and chlorophyll metabolism  hsa00860+210  
According to Reactome, this protein belongs to the following pathway:
Heme biosynthesis  REACT_9465  
 
More information is available from:
 

Biophysicochemical properties

Kinetic parameters
KM 0.09 mM for 5-aminolevulinate at pH 7
Vmax 43 umol/h/mg enzyme at pH 7
Dependence
pH Optimum pH is 6.8-7.3.

Keywords

Biological process 
Heme biosynthesis  definition   [KW-0350]
Porphyrin biosynthesis  definition   [KW-0627]
Molecular function 
Lyase  definition   [KW-0456]
Technical term 
Allosteric enzyme  definition   [KW-0021]
Reference proteome  definition   [KW-1185]
 

Further external links

GeneWiki: ALAD
GenomeRNAi: 210
PRO: PR:P13716