ABCB4 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. Plays a role in the recruitment of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM) molecules to nonraft membranes and to further enrichment of SM and cholesterol in raft membranes in hepatocytes. Required for proper phospholipid bile formation. Indirectly involved in cholesterol efflux activity from hepatocytes into the canalicular lumen in the presence of bile salts in an ATP-dependent manner. Promotes biliary phospholipid secretion as canaliculi-containing vesicles from the canalicular plasma membrane. In cooperation with ATP8B1, functions to protect hepatocytes from the deleterious detergent activity of bile salts. Does not confer multidrug resistance. Belongs to the ABC transporter superfamily. ABCB family. Multidrug resistance exporter (TC 3.A.1.201) subfamily. 3 alternatively spliced human isoforms have been reported. Note: This description may include information from UniProtKB.
Protein type: EC; Hydrolase; Membrane protein, integral; Membrane protein, multi-pass; Transporter; Transporter, ABC family
Chromosomal Location of mouse Ortholog: 5 A1|5 3.43 cM
Cellular Component:  actin cytoskeleton; apical plasma membrane; cytoplasm; cytoplasmic vesicle; cytosol; focal adhesion; Golgi membrane; intercellular canaliculus; membrane; nucleoplasm; plasma membrane
Molecular Function:  ABC-type transporter activity; ATP binding; ATPase-coupled intramembrane lipid transporter activity; ATPase-coupled transmembrane transporter activity; ceramide floppase activity; nucleotide binding; phosphatidylcholine floppase activity; phosphatidylethanolamine flippase activity; xenobiotic transmembrane transporter activity
Biological Process:  bile acid secretion; cellular response to bile acid; lipid homeostasis; lipid transport; phospholipid translocation; positive regulation of cholesterol transport; positive regulation of phospholipid translocation; positive regulation of phospholipid transport; response to fenofibrate; transmembrane transport; xenobiotic transmembrane transport
Reference #:  P21440 (UniProtKB)
Alt. Names/Synonyms: Abcb4; ATP-binding cassette sub-family B member 4; ATP-binding cassette, sub-family B (MDR/TAP), member 4; Mdr; mdr-; mdr-2; Mdr2; MDR3; Multidrug resistance protein 2; Multidrug resistance protein 3; P glycoprotein 2; P-glycoprotein 2; P-glycoprotein 3; Pgy; Pgy-; Pgy-2; Pgy2; Phosphatidylcholine translocator ABCB4
Gene Symbols: Abcb4
Molecular weight: 140,377 Da
Basal Isoelectric point: 8.88  Predict pI for various phosphorylation states
Select Structure to View Below


Protein Structure Not Found.

Cross-references to other databases:  AlphaFold  |  STRING  |  Reactome  |  BioGPS  |  Pfam  |  ENZYME  |  Phospho.ELM  |  NetworKIN  |  UniProtKB  |  Entrez-Gene  |  GenPept  |  Ensembl Gene