UGT1A4
UDP glucuronosyltransferase family 1 member A4
Named by Dr Will Powers — at family level only
Gene summary
A protein-coding gene on chromosome 2 (steroid conjugation and clearance). Encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases.
Source: NCBI Gene, accessed 2026-10-07.
Protein reference (UniProt)
- Protein
UDP-glucuronosyltransferase 1A4
- Function (excerpt)
Isoform 1: UDP-glucuronosyltransferase (UGT) that catalyzes phase II biotransformation reactions in which lipophilic substrates are conjugated with glucuronic acid to increase the metabolite's water solubility, thereby facilitating excretion into either the urine or bile. Essential for the elimination and detoxification of drugs, xenobiotics and endogenous compounds. Involved in the glucuronidation of calcidiol, which is the major circulating form of vitamin D3 essential for the regulation of calcium and phosphate homeostasis. Also glucuronidates the biologically active form of vitamin D3, calcitriol, probably leading to its biliary transport and intestinal reabsorption. Involved in the glucuronidation of arachidonic acid (AA) and AA-derived eicosanoids including 15-HETE, 20-HETE and PGB1. Catalyzes N-glucuronidation of tobacco alkaloids, tobacco-specific nitrosamines and tricyclic antidepressants.
- Subcellular location
Endoplasmic reticulum membrane.
- Tissue specificity
Isoform 1: Expressed in liver. Expressed in kidney, colon and small intestine. Not expressed in esophagus. Not expressed in skin. Isoform 2: Expressed in liver, kidney, colon, esophagus and small intestine.
Source: UniProtKB/Swiss-Prot P22310, 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
Steroid clearance is the exit route for androgens and their metabolites — the pathway at the center of Powers' PFS model (defective glucuronidation/sulfation trapping androgens intracellularly). Gut bacterial enzymes can undo this clearance, linking it to the microbiome thread.
Written for the whole conjugation & clearance family, not for UGT1A4 specifically.
Powers’ note (his unpublished theorizing)
Covered by Powers' general claim (DWP-002, unpublished) that defective glucuronidation underlies his PFS phenotype (>50% of his PFS patients show ~zero urinary androgens on DUTCH testing); not individually named by him.
Mentioned in 0 corpus records
No corpus record names UGT1A4 directly yet. It is in the library because it sits in a pathway the corpus tracks (Conjugation & clearance).
Also in steroid conjugation and clearance
All 31 genes- UGT2B17Powers
UDP glucuronosyltransferase family 2 member B17
chr 4· Conjugation & clearance· 30 records - UGT2B15Powers
UDP glucuronosyltransferase family 2 member B15
chr 4· Conjugation & clearance· 13 records - AKR1C2Powers
aldo-keto reductase family 1 member C2
chr 10· Steroid synthesis· 12 records - UGT2B7Powers
UDP glucuronosyltransferase family 2 member B7
chr 4· Conjugation & clearance· 11 records - AKR1C3Powers
aldo-keto reductase family 1 member C3
chr 10· Steroid synthesis· 9 records - AKR1C4Powers
aldo-keto reductase family 1 member C4
chr 10· Steroid synthesis· 8 records - AKR1C1Powers
aldo-keto reductase family 1 member C1
chr 10· Steroid synthesis· 7 records - SULT2A1Powers
sulfotransferase family 2A member 1
chr 19· Conjugation & clearance· 7 records
Browse by family on the gene families page.