Pathway candidateNCBI-verifiedprotein-coding

ABCB4

ATP binding cassette subfamily B member 4

NCBI Gene: 5244 Ensembl GeneCards UniProt: P21439

Pathway candidate — not linked to PFS or PSSD by any record here

ABCB4 is in the library because it belongs to the drug transporters family. No study, report or commentary in the corpus names it, so a variant in ABCB4 is not, by itself, evidence of anything related to post-drug syndromes.

Gene summary

A protein-coding gene on chromosome 7 (drug and xenobiotic transporters). The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes.

Source: NCBI Gene, accessed 2026-10-07.

Protein reference (UniProt)

Protein: Phosphatidylcholine translocator ABCB4
Function (excerpt): Isoform 1: 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 (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.
Subcellular location: Cell membrane; Apical cell membrane; Membrane raft; Cytoplasm; Cytoplasmic vesicle, clathrin-coated vesicle.
Associated conditions: Cholestasis, progressive familial intrahepatic, 3 (PFIC3); Cholestasis of pregnancy, intrahepatic 3 (ICP3); Gallbladder disease 1 (GBD1).

Source: UniProtKB/Swiss-Prot P21439, release 2026_03, licensed CC BY 4.0. This is the protein’s normal biology, not evidence about post-drug syndromes; associated conditions are inherited disorders of the gene, not PFS, PSSD or PRSD.

Why its pathway is in the library

Transporters set systemic exposure to finasteride/SSRIs and clear conjugated steroid metabolites — directly relevant to both drug pharmacokinetics and Powers' clearance-centered PFS mechanism.

Written for the whole drug transporters family, not for ABCB4 specifically.

Mentioned in 0 corpus records

No corpus record names ABCB4 directly yet. It is in the library because it sits in a pathway the corpus tracks (Drug transporters).

Also in drug and xenobiotic transporters

All 62 genes

Browse by family on the gene families page.

Gene summary

Source: NCBI Gene, accessed 2026-10-07.

Protein reference (UniProt)

Protein: Phosphatidylcholine translocator ABCB4
Function (excerpt): Isoform 1: 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 (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.
Subcellular location: Cell membrane; Apical cell membrane; Membrane raft; Cytoplasm; Cytoplasmic vesicle, clathrin-coated vesicle.
Associated conditions: Cholestasis, progressive familial intrahepatic, 3 (PFIC3); Cholestasis of pregnancy, intrahepatic 3 (ICP3); Gallbladder disease 1 (GBD1).