Pathway Human Homo sapiens

Endogenous sterols

R-HSA-211976 in Reactome release 97: under Cytochrome P450 - arranged by substrate type, with 26 genes placed in it by the mapping files and 1 child pathway in the hierarchy.

The same number in the other species

Reactome writes the mouse and rat events it infers from a human pathway under the human number with the species token. A door opens only where that species' own list in this release holds the id: R-MMU-211976 (mouse), R-RNO-211976 (rat). Whether the event was inferred from this one is what the record says.

The record
The genes
Parents and children

Scripts are off

This page reads the pathway's record from its source while you read the rest; with scripts off the card stays at its loading line. Reload with scripts on to see it, or open the source's own page from the link in the card.

01The record

Reactome's own record of this pathway

What this tells you

The pathway list, the hierarchy and the genes on this page are read from the files Reactome publishes for Reactome release 97, built into this site on 2026-09-09: the pathway list, the hierarchy relationship file and the two gene mapping files. The record card is the one live read, Reactome's own record of this pathway.

Reactome's download page describes the mapping files: Mapping files link the source database identifier to the lowest level pathway diagram or subset of the pathway, all levels of the pathway hierarchy or database identifier to all reactions. [R13] The gene list here is the all-levels mapping of NCBI Gene ids, filled from the all-levels mapping of Ensembl ids where the NCBI file has no row for a gene; each row names which file it came from by the shape of its source id. Each row carries the evidence codes the file writes for it, as written and unranked, and both where the file writes both; no page of Reactome's documentation the survey read defines the codes, so this page does not expand them. A gene id the identity files do not name is kept as the source's own id with no door rather than turned into a symbol.

On citing what a search finds, Reactome says: It should be remembered that while we strive to contain the most current and accurate data, Reactome should not be used in citations where other primary sources of information are available. [R12] The record card prints the literature Reactome attaches to a curated pathway for that reason. The data are public domain: All data in the Reactome database and files derived from that data are licensed under the Creative Commons Public Domain Dedication (CC0). User may copy, modify, and distribute these data, even for commercial purposes, without asking for permission. Attribution is encouraged but not required. [R10] The pathway illustrations are licensed apart, under CC BY 4.0, and none is shown here.

A gene on this list is one Reactome places in this pathway in this release, and that is all the row says: it does not say the gene is expressed in a tissue or associated with a disease, which are the other two explorers' questions, read from other sources. Reactome's papers of record are [R01] [R02].

[R01] Ragueneau E, Gong C, Sinquin P, Sevilla C, Beavers D, Grentner A, et al. (2026). The Reactome Knowledgebase 2026. Nucleic Acids Research 54:D673-D681. PMID 41251150, doi 10.1093/nar/gkaf1223.
[R02] Milacic M, Beavers D, Conley P, Gong C, Gillespie M, Griss J, et al. (2024). The Reactome Pathway Knowledgebase 2024. Nucleic Acids Research 52:D672-D678. PMID 37941124, doi 10.1093/nar/gkad1025.
[R10] Reactome, reactome.org. License Agreement. https://reactome.org/license, read 2026-09-09.
[R12] Reactome, reactome.org. Citing us. https://reactome.org/cite, read 2026-09-09.
[R13] Reactome, reactome.org. Download. https://reactome.org/download-data, read 2026-09-09.

Stable id: R-HSA-211976.8
Class: Pathway
Species: Homo sapiens (human)
Inferred: no: a curated human pathway
Disease pathway: no
Released: 2008-06-30
Last updated: 2018-12-13
Events inside: 16, counted from the record

A number of CYPs take part in cholesterol biosynthesis and elimination, thus playing an important role in maintaining cholesterol homeostasis. Under normal physiological conditions, cholesterol intake (diet or synthesized de novo from acetyl CoA) equals cholesterol elimination (degraded to bile salts, secreted in bile and used in steroid hormone synthesis). These processes are under tight regulatory control and any disruption leads to increased cholesterol levels resulting in cardiovacular disease. The CYPs involved in cholesterol homeostasis could serve as potential targets for cholesterol-lowering drugs (Lewis 2004, Guengerich 2006, Pikuleva 2006).

Literature Reactome attaches

57 varieties: the human cytochromes P450Pharmacogenomics, 2004, vol. 5, p. 305-18PubMed 15102545
Cytochrome P450s and other enzymes in drug metabolism and toxicityAAPS J, 2006, vol. 8, p. E101-11PubMed 16584116
Cytochrome P450s and cholesterol homeostasisPharmacol Ther, 2006, vol. 112, p. 761-73PubMed 16872679

Reactome's record lists 13 orthologous events, R-MMU-211976 (Mus musculus), R-RNO-211976 (Rattus norvegicus) among the species this site serves, and 11 in species this site opens no page for.

Reactome ContentService, this pathway's record · Reactome v97 · read 2026-10-01 ET · Reactome pathway browser"Endogenous sterols". Reactome, release 97, https://reactome.org/PathwayBrowser/#/R-HSA-211976 with StableID: R-HSA-211976.8 (accessed 2026-10-01 ET). Reactome version 97 (CC0).

Reading this pathway's record from Reactome (the pathway record).Still reading. A first read of a pathway can take a while; this page waits up to 35 seconds for it, and its scripts then bring in the panel, or a line saying what did not arrive.

02The genes

Genes Reactome places in this human pathway

The mapping files place 26 genes in this human pathway; showing 1 to 26, in pages of 100, sorted by symbol for reading. The order carries no ranking.

Genes Reactome places in this human pathway, page 1 of 1
Gene	Authority id	Mapping file id	Evidence codes
GeneAHR	AuthorityHGNC:348	Mapping file id196 NCBI file	EvidenceTAS
GeneAHRR	AuthorityHGNC:346	Mapping file id57491 NCBI file	EvidenceTAS
GeneARNT	AuthorityHGNC:700	Mapping file id405 NCBI file	EvidenceTAS
GeneARNT2	AuthorityHGNC:16876	Mapping file id9915 NCBI file	EvidenceTAS
GeneCYP11A1	AuthorityHGNC:2590	Mapping file id1583 NCBI file	EvidenceTAS
GeneCYP11B1	AuthorityHGNC:2591	Mapping file id1584 NCBI file	EvidenceTAS
GeneCYP11B2	AuthorityHGNC:2592	Mapping file id1585 NCBI file	EvidenceTAS
GeneCYP19A1	AuthorityHGNC:2594	Mapping file id1588 NCBI file	EvidenceTAS
GeneCYP1B1	AuthorityHGNC:2597	Mapping file id1545 NCBI file	EvidenceTAS
GeneCYP21A2	AuthorityHGNC:2600	Mapping file id1589 NCBI file	EvidenceTAS
GeneCYP27A1	AuthorityHGNC:2605	Mapping file id1593 NCBI file	EvidenceTAS
GeneCYP39A1	AuthorityHGNC:17449	Mapping file id51302 NCBI file	EvidenceTAS
GeneCYP46A1	AuthorityHGNC:2641	Mapping file id10858 NCBI file	EvidenceTAS
GeneCYP4V2	AuthorityHGNC:23198	Mapping file id285440 NCBI file	EvidenceTAS
GeneCYP51A1	AuthorityHGNC:2649	Mapping file id1595 NCBI file	EvidenceTAS
GeneCYP7A1	AuthorityHGNC:2651	Mapping file id1581 NCBI file	EvidenceTAS
GeneCYP7B1	AuthorityHGNC:2652	Mapping file id9420 NCBI file	EvidenceTAS
GeneCYP8B1	AuthorityHGNC:2653	Mapping file id1582 NCBI file	EvidenceTAS
GeneFDX1	AuthorityHGNC:3638	Mapping file id2230 NCBI file	EvidenceTAS
GeneFDX2	AuthorityHGNC:30546	Mapping file id112812 NCBI file	EvidenceTAS
GeneFDXR	AuthorityHGNC:3642	Mapping file id2232 NCBI file	EvidenceTAS
GeneNCOA1	AuthorityHGNC:7668	Mapping file id8648 NCBI file	EvidenceTAS
GeneNCOA2	AuthorityHGNC:7669	Mapping file id10499 NCBI file	EvidenceTAS
GeneNR1H4	AuthorityHGNC:7967	Mapping file id9971 NCBI file	EvidenceTAS
GenePOMC	AuthorityHGNC:9201	Mapping file id5443 NCBI file	EvidenceTAS
GeneRXRA	AuthorityHGNC:10477	Mapping file id6256 NCBI file	EvidenceTAS

Evidence codes on this page: TAS, as the mapping file writes them; a row carrying two was written twice by the file, once under each. The mapping file id says which file placed the gene: an NCBI Gene id from NCBI2Reactome_All_Levels.txt, an Ensembl gene id from Ensembl2Reactome_All_Levels.txt. The two files can disagree about a code, so a row's codes are the one file's view. Measured by this site's build over this release on 2026-09-09: of the 138,908 human pathway-gene pairs both files place, 207 (0.149 per cent, over 47 genes) carry TAS in the Ensembl file where the NCBI rows carry IEA alone.

Reactome mapping files, the human rows for this pathway · Reactome release 97 · read 2026-09-09 · Reactome downloads"NCBI2Reactome_All_Levels.txt" and "Ensembl2Reactome_All_Levels.txt", Reactome, release 97, https://reactome.org/download-data/ (date of access 2026-09-09). Data CC0; attribution encouraged.

03The hierarchy

Parents and children in this release's hierarchy

Parents

Cytochrome P450 - arranged by substrate typeR-HSA-21189767 genes

Children

Sterols are 12-hydroxylated by CYP8B1R-HSA-2119941 genes

Reactome's hierarchy is a graph rather than a tree: a pathway can sit under more than one parent, and the gene counts are each pathway's own placements at every level under it, so a parent's count is not the sum of its children's.

Reactome, the human pathway list and hierarchy relationship file · Reactome release 97 · read 2026-09-09 · Reactome downloads"ReactomePathways.txt" and "ReactomePathwaysRelation.txt", Reactome, release 97, https://reactome.org/download-data/ (date of access 2026-09-09). Data CC0; attribution encouraged.