UGT1A1 - UDP-glucuronosyltransferase 1-1 - human protein (Function)
 
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Protein
Gene
References

 
UGT1A1 »  UDP-glucuronosyltransferase 1-1   [ EC 2.4.1.17 ]  (UGT1*1)
 
Protein also known as:  Bilirubin-specific UDPGT isozyme 1.
Gene name:  UGT1A1
Entry whose protein(s) existence is based on evidence at protein level
extend overview
1 301 2
GENE REF ISO

Function

 show evidences
Overview 
UDPGT is of major importance in the conjugation and subsequent elimination of potentially toxic xenobiotics and endogenous compounds. This isoform glucuronidates bilirubin IX-alpha to form both the IX-alpha-C8 and IX-alpha-C12 monoconjugates and diconjugate. Is also able to catalyze the glucuronidation of 17beta-estradiol, 17alpha-ethinylestradiol, 1-hydroxypyrene, 4-methylumbelliferone, 1-naphthol, paranitrophenol, scopoletin, and umbelliferone.  
5
  • CuratedUniProtKB
Isoform  Iso 2   Lacks transferase activity but acts as a negative regulator of isoform 1.  
5
  • CuratedUniProtKB
GO molecular function 
Enzyme bindingdefinition[GO:0019899]  
1
  • IDABHF-UCL
Enzyme inhibitor activitydefinition[GO:0004857]  
1
  • IDABHF-UCL
Glucuronosyltransferase activitydefinition[GO:0015020]  
6
  • IDAUniProtKB
  • IDABHF-UCL
Protein heterodimerization activitydefinition[GO:0046982]  
2
  • IPIBHF-UCL
  • IDAUniProtKB
Protein homodimerization activitydefinition[GO:0042803]  
2
  • IPIBHF-UCL
  • IDAUniProtKB
Retinoic acid bindingdefinition[GO:0001972]  
1
  • IDABHF-UCL
Steroid bindingdefinition[GO:0005496]  
1
  • IDABHF-UCL
GO biological process 
Acute-phase responsedefinition[GO:0006953] silver  
  • IEAOrtholog Compara
Bilirubin conjugationdefinition[GO:0006789]  
1
  • TASPINC
Biphenyl catabolic processdefinition[GO:0070980] silver  
  • IEAOrtholog Compara
Cellular glucuronidationdefinition[GO:0052695]  
2
  • IDAUniProtKB
Cellular response to ethanoldefinition[GO:0071361] silver  
  • IEAOrtholog Compara
Cellular response to glucocorticoid stimulusdefinition[GO:0071385] silver  
  • IEAOrtholog Compara
Digestiondefinition[GO:0007586]  
1
  • NASPINC
Drug metabolic processdefinition[GO:0017144]  
1
  • ICBHF-UCL
Estrogen metabolic processdefinition[GO:0008210]  
1
  • TASPINC
Flavone metabolic processdefinition[GO:0051552]  
1
  • IDABHF-UCL
Flavonoid glucuronidationdefinition[GO:0052696]  
1
  • IDABHF-UCL
Heterocycle metabolic processdefinition[GO:0046483]  
1
  • ICBHF-UCL
Liver developmentdefinition[GO:0001889] silver  
  • IEAOrtholog Compara
Negative regulation of catalytic activitydefinition[GO:0043086]  
1
  • IDAGOC
Isoform  Iso 2   Negative regulation of cellular glucuronidationdefinition[GO:2001030]  
1
  • IDAUniProtKB
Negative regulation of steroid metabolic processdefinition[GO:0045939]  
1
  • ICBHF-UCL
Organ regenerationdefinition[GO:0031100] silver  
  • IEAOrtholog Compara
Response to drugdefinition[GO:0042493] silver  
  • IEAOrtholog Compara
Response to lipopolysaccharidedefinition[GO:0032496] silver  
  • IEAOrtholog Compara
Response to nutrientdefinition[GO:0007584] silver  
  • IEAOrtholog Compara
Response to starvationdefinition[GO:0042594] silver  
  • IEAOrtholog Compara
Retinoic acid metabolic processdefinition[GO:0042573]  
1
  • ICBHF-UCL
Steroid metabolic processdefinition[GO:0008202]  
1
  • ICBHF-UCL
Xenobiotic glucuronidationdefinition[GO:0052697]  
1
  • IDABHF-UCL
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 2.4.1.17: UDP-glucuronate + acceptor UDP + acceptor beta-D-glucuronoside.  
2
  • CuratedUniProtKB
According to CAZy, this protein is belongs to the following pathway:
Glycosyltransferase Family 1  GT1  
Pathways 
According to KEGG, this protein belongs to the following pathways:
Ascorbate and aldarate metabolism  hsa00053+54658  
Drug metabolism - cytochrome P450  hsa00982+54658  
Drug metabolism - other enzymes  hsa00983+54658  
Metabolic pathways  hsa01100+54658  
Metabolism of xenobiotics by cytochrome P450  hsa00980+54658  
Other types of O-glycan biosynthesis  hsa00514+54658  
Pentose and glucuronate interconversions  hsa00040+54658  
Porphyrin and chlorophyll metabolism  hsa00860+54658  
Retinol metabolism  hsa00830+54658  
Starch and sucrose metabolism  hsa00500+54658  
Steroid hormone biosynthesis  hsa00140+54658  
According to Reactome, this protein belongs to the following pathways:
Glucuronidation  REACT_6784  
Heme degradation  REACT_22297  
Note 
The gene is part of the UGT1A complex locus which displays alternative use of promoters, first exons and terminal exons. The locus is defined by 13 first exons, which are alternatively spliced to 3 other common exons and 2 alternative terminal exons 5. From the 27 possible mRNA isoforms, 9 produce functionally active polypeptides (UGT1A1, 1A3, 1A4, 1A5, 1A6, 1A7, 1A8, 1A9 and 1A10) called isoforms 1 (i1). Use of an alternative exon 5 (5b) as terminal exon is leading to 9 additional alternatively spliced products termed isoforms i2 and which lack transferase activity.  
  • CuratedUniProtKB
 

Biophysicochemical properties

Kinetic parameters
KM 0.26 uM for bilirubin
Vmax 1080 pmol/min/mg enzyme with bilirubin as substrate

Keywords

Molecular function 
Glycosyltransferase  definition   [KW-0328]
Transferase  definition   [KW-0808]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

Enzyme and pathway databases
SABIO-RK: P22309
Other
GenomeRNAi: 54658
PRO: PR:P22309