ABCB4 - Phosphatidylcholine translocator ABCB4 - human protein (Function)
 
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Protein
Gene
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ABCB4 »  Phosphatidylcholine translocator ABCB4
 
Protein also known as:  ATP-binding cassette sub-family B member 4.
Gene name:  ABCB4
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 
Energy-dependent phospholipid efflux translocator that acts as a positive regulator of biliary lipid secretion. Functions as a floppase that translocates specifically phosphatidylcholine (PC) from the inner to the outer leaflet of the canalicular membrane bilayer into the canaliculi of hepatocytes. Translocation of PC makes the biliary phospholipids available for extraction into the canaliculi lumen by bile salt mixed micelles and therefore protects the biliary tree from the detergent activity of bile salts (PubMed7957936, PubMed8898203, PubMed9366571, PubMed17523162, PubMed23468132, PubMed24806754, PubMed24723470, PubMed24594635, PubMed21820390). Plays a role in the recruitment of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM) molecules to nonraft membranes and to fu rther enrichment of SM and cholesterol in raft membranes in hepatocytes (PubMed23468132). Required for proper phospholipid bile formation (By similarity). Indirectly involved in cholesterol efflux activity from hepatocytes into the canalicular lumen in the presence of bile salts in an ATP-dependent manner (PubMed24045840). May promote biliary phospholipid secretion as canaliculi-containing vesicles from the canalicular plasma membrane (PubMed9366571). In cooperation with ATP8B1, functions to protect hepatocytes from the deleterious detergent activity of bile salts (PubMed21820390). Does not confer multidrug resistance (By similarity).  
12
  • UniProtKB
According to TCDB this is a transporter from family:
the atp-binding cassette (abc) superfamily  3.A.1.201.3  
GO molecular function 
ATP bindingdefinition[GO:0005524]  
1
  • UniProtKB KW
ATPase activity, coupled to transmembrane movement of substancesdefinition[GO:0042626]  
2
  • UniProtKB
Phosphatidylcholine transporter activitydefinition[GO:0008525]  
2
  • UniProtKB
Phosphatidylcholine-translocating ATPase activitydefinition[GO:0090554]  
2
  • UniProtKB
Protein bindingdefinition[GO:0005515]  
1
  • UniProtKB
Xenobiotic-transporting ATPase activitydefinition[GO:0008559]  
1
  • EC 2 GO
GO biological process 
Bile acid secretiondefinition[GO:0032782]  
1
  • Ortholog Curator
Cellular response to bile aciddefinition[GO:1903413]  
1
  • UniProtKB
Drug transmembrane transportdefinition[GO:0006855]  
1
  • EC 2 GO
Lipid homeostasisdefinition[GO:0055088]  
1
  • UniProtKB
Lipid metabolic processdefinition[GO:0006629]  
1
  • PINC
Phospholipid translocationdefinition[GO:0045332]  
1
  • UniProtKB
Positive regulation of cholesterol transportdefinition[GO:0032376]  
2
  • UniProtKB
Positive regulation of phospholipid translocationdefinition[GO:0061092]  
1
  • UniProtKB
Positive regulation of phospholipid transportdefinition[GO:2001140]  
2
  • UniProtKB
Response to drugdefinition[GO:0042493]  
1
  • PINC
Response to fenofibratedefinition[GO:1901557]  
1
  • Ortholog Curator
Transmembrane transportdefinition[GO:0055085]  
1
  • RefGenome
Transportdefinition[GO:0006810]  
1
  • PINC
Xenobiotic transportdefinition[GO:0042908]  
1
  • EC 2 GO
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 3.6.3.44: ATP + H(2)O + xenobiotic(In) ADP + phosphate + xenobiotic(Out).  
1
  • UniProtKB
It is regulated in the following manner
Translocation activity is inhibited by the ATPase inhibitor vanadate and the calcium channel blocker verapamil (PubMed17523162, PubMed23468132). Translocation activity is enhanced by the addition of the bile salt taurocholate (PubMed17523162, PubMed23468132).  
3
  • UniProtKB
Pathways 
According to KEGG, this protein belongs to the following pathways:
ABC transporters  hsa02010+5244  
Bile secretion  hsa04976+5244  
According to Reactome, this protein belongs to the following pathways:
ABC-family proteins mediated transport  R-HSA-382556  
Defective ABCB4 causes progressive familial intrahepatic cholestasis 3, intrahepatic cholestasis of pregnancy 3 and gallbladder disease 1  R-HSA-5678771  
PPARA activates gene expression  R-HSA-1989781  
 

Keywords

Biological process 
Lipid transport  definition   [KW-0445]
Transport  definition   [KW-0813]
Molecular function 
Hydrolase  definition   [KW-0378]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

Other
GeneWiki: ABCB4
GenomeRNAi: 5244
PRO: PR:P21439
Chemistry
SwissLipids: SLP:000000384