CH25H

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005789 endoplasmic reticulum membrane	IBA GO_REF:0000033	ACCEPT	Summary: Correct core localization. CH25H is an ER-membrane multi-pass integral membrane protein; UniProt reports ER membrane localization and three transmembrane helices. The phylogenetic (IBA) inference agrees with experimental/ISS localization. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt CC -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane CC {ECO:0000250\|UniProtKB:Q9Z0F5}; Multi-pass membrane protein CC {ECO:0000250\|UniProtKB:Q9Z0F5}.
GO:0001567 cholesterol 25-hydroxylase activity	IBA GO_REF:0000033	ACCEPT	Summary: This is the core molecular function of CH25H. The phylogenetic inference matches the experimentally demonstrated cholesterol 25-hydroxylase activity (EC 1.14.99.38). Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt Catalyzes the formation of 25-hydroxycholesterol from
GO:0036197 zymosterol biosynthetic process	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: Over-annotation arising from phylogenetic (IBA) propagation across the sterol desaturase / fatty acid hydroxylase family. CH25H hydroxylates cholesterol at C-25; it does not act on zymosterol and is not part of zymosterol biosynthesis. Its demonstrated substrate is cholesterol. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN002275159 · sterol desaturase family node SUPPORTS SOURCE BUT NOT TARGET Family node for methylsterol/zymosterol-processing members; CH25H diverged to C-25 hydroxylation of cholesterol. MGI:MGI:1913484 · Msmo1 (mouse) SUPPORTS SOURCE BUT NOT TARGET Methylsterol oxidase acting in zymosterol biosynthesis; not the substrate/role of CH25H. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt Catalyzes the formation of 25-hydroxycholesterol from
GO:0000254 C-4 methylsterol oxidase activity	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: Over-annotation from phylogenetic propagation within the sterol desaturase family. CH25H's demonstrated activity is C-25 hydroxylation of cholesterol, not C-4 demethylation/oxidation of methylsterols (the activity of SC4MOL/MSMO1-type family members). The specific, evidence-supported function is cholesterol 25-hydroxylase activity. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Sources checked: UniProtKB:Q15800 · MSMO1 (human) SUPPORTS SOURCE BUT NOT TARGET Bona fide C-4 methylsterol oxidase; CH25H shares the fatty-acid-hydroxylase/histidine-box fold but hydroxylates cholesterol at C-25. SGD:S000003292 · ERG25 (yeast) SUPPORTS SOURCE BUT NOT TARGET C-4 methylsterol oxidase of ergosterol biosynthesis; family-level activity that did not transfer to CH25H's true function. PANTHER:PTN000221246 · sterol desaturase family node SUPPORTS SOURCE BUT NOT TARGET Broad family node; C-4 methylsterol oxidase activity is over-general for CH25H. Supporting Evidence: PMID:9852097 Here, we report the cloning of cholesterol
GO:0001567 cholesterol 25-hydroxylase activity	IEA GO_REF:0000120	ACCEPT	Summary: Correct core molecular function, redundant with the experimental annotations to the same term. The automated IEA (via ortholog Q9Z0F5, RHEA, and EC:1.14.99.38) agrees with experiment. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt Catalyzes the formation of 25-hydroxycholesterol from
GO:0005506 iron ion binding	IEA GO_REF:0000002	ACCEPT	Summary: Biologically correct and consistent with the enzyme mechanism. CH25H is a diiron enzyme (not a heme/P450); UniProt records an Fe cation cofactor and the conserved histidine-box motifs coordinate the diiron center. Iron ion binding is part of the catalytic machinery. Supporting Evidence: PMID:9852097 it is a member of a small family of enzymes that utilize diiron
GO:0005789 endoplasmic reticulum membrane	IEA GO_REF:0000044	ACCEPT	Summary: Correct core localization, derived from the UniProt subcellular-location mapping. Consistent with the experimental/ISS and IBA ER-membrane annotations. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt CC -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane CC {ECO:0000250\|UniProtKB:Q9Z0F5}; Multi-pass membrane protein CC {ECO:0000250\|UniProtKB:Q9Z0F5}.
GO:0008610 lipid biosynthetic process	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: Correct but very general (grand-parent-level) InterPro2GO annotation. CH25H synthesizes the oxysterol 25-hydroxycholesterol, so lipid biosynthesis is true but uninformative; the specific process is oxysterol/sterol/cholesterol metabolism. Kept as non-core because more specific terms are annotated. Supporting Evidence: PMID:9852097 cholesterol 25-hydroxylases, polytopic membrane proteins that synthesize a potent oxysterol regulator of lipid metabolism
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome.	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" from a large-scale binary interactome screen (HuRI); the reported partners (KRTAP12-4 / P60329; OTX1 / P32242, a keratin-associated protein and a homeobox transcription factor) have no clear functional relationship to a cholesterol-hydroxylating ER enzyme and are typical high-throughput Y2H hits. The term is uninformative about CH25H's molecular function. Retained (experimental IPI) but flagged as over-annotated; not used as a core function.
GO:0035754 B cell chemotaxis	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: Downstream/indirect physiological role transferred from the mouse ortholog. CH25H does not itself have chemotactic activity; its product 25-HC is converted to 7alpha,25-dihydroxycholesterol, a GPR183/EBI2 ligand that guides B-cell positioning. Biologically reasonable but indirect and non-core. Supporting Evidence: PMID:33239446 25HC is further converted to 7-α, 25-dihydroxycholesterol (7-α, 25-diHC), an oxysterol that functions as a chemoattractant for T cells and B cells
GO:0090206 negative regulation of cholesterol metabolic process	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: Captures the well-established regulatory role of 25-HC as an SREBP co-repressor that suppresses cholesterol biosynthesis. Transferred electronically from the mouse ortholog but supported by human experimental work showing reduced cholesterol synthesis and blocked SREBP processing. Regulatory and downstream of the catalytic MF, so kept as non-core. Supporting Evidence: PMID:9852097 the biosynthesis of cholesterol from acetate and suppresses the cleavage of
GO:0001567 cholesterol 25-hydroxylase activity	EXP PMID:33239446 Cholesterol 25-hydroxylase suppresses SARS-CoV-2 replication...	ACCEPT	Summary: Core molecular function, directly demonstrated. The catalytic His-His double mutant abolished 25-HC production, confirming CH25H is the enzyme producing 25-HC from cholesterol. Supporting Evidence: PMID:33239446 mutant CH25H did not produce 25HC and 7-α, 25-diHC
GO:0001567 cholesterol 25-hydroxylase activity	EXP PMID:9852097 cDNA cloning of mouse and human cholesterol 25-hydroxylases,...	ACCEPT	Summary: Core molecular function, from the original cloning and catalytic characterization of human and mouse cholesterol 25-hydroxylases. Establishes the diiron, non-P450 nature of the enzyme. Supporting Evidence: PMID:9852097 Here, we report the cloning of cholesterol
GO:0005789 endoplasmic reticulum membrane	ISS GO_REF:0000024	ACCEPT	Summary: Correct core localization, inferred by sequence similarity from the mouse ortholog (Q9Z0F5). Consistent with the multi-pass membrane topology and the IBA/IEA ER-membrane annotations. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt CC -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane CC {ECO:0000250\|UniProtKB:Q9Z0F5}; Multi-pass membrane protein CC {ECO:0000250\|UniProtKB:Q9Z0F5}.
GO:0001567 cholesterol 25-hydroxylase activity	IDA PMID:32944968 Cholesterol 25-Hydroxylase inhibits SARS-CoV-2 and other cor...	ACCEPT	Summary: Core molecular function, directly assayed. CH25H converts cholesterol to 25-hydroxycholesterol; this study demonstrates production of 25-HC and its antiviral consequences in human cells. Supporting Evidence: PMID:32944968 CH25H converts cholesterol to 25-hydrocholesterol (25HC)
GO:0008203 cholesterol metabolic process	IDA PMID:33239446 Cholesterol 25-hydroxylase suppresses SARS-CoV-2 replication...	ACCEPT	Summary: Correct core biological process: CH25H catalyzes a step of cholesterol/oxysterol metabolism, converting cholesterol to 25-HC. Directly supported by the demonstrated catalytic activity. Supporting Evidence: PMID:33239446 CH25H encodes cholesterol 25-hydroxylase that catalyzes the formation of 25-hydroxycholesterol (25HC) from cholesterol
GO:0034340 response to type I interferon	IDA PMID:33239446 Cholesterol 25-hydroxylase suppresses SARS-CoV-2 replication...	ACCEPT	Summary: CH25H is an interferon-stimulated gene induced during antiviral responses; this is a genuine and important biological context. It is a regulatory/context process rather than the enzyme's core catalytic function, but it is well supported experimentally. Supporting Evidence: PMID:33239446 Cholesterol 25-hydroxylase (CH25H) is an interferon (IFN)-stimulated gene that
GO:1903914 negative regulation of fusion of virus membrane with host plasma membrane	IDA PMID:32944968 Cholesterol 25-Hydroxylase inhibits SARS-CoV-2 and other cor...	ACCEPT	Summary: Well-supported antiviral biological process. CH25H/25-HC blocks coronavirus spike-mediated membrane fusion by activating ER ACAT and depleting accessible plasma-membrane cholesterol. Supporting Evidence: PMID:32944968 These results strongly support a function for 25HC in blocking human coronavirus spike
GO:1903914 negative regulation of fusion of virus membrane with host plasma membrane	IDA PMID:33239446 Cholesterol 25-hydroxylase suppresses SARS-CoV-2 replication...	ACCEPT	Summary: Well-supported antiviral biological process (independent confirmation). CH25H expression and 25-HC block SARS-CoV-2 spike-mediated membrane fusion; the catalytic mutant, which cannot make 25-HC, loses antiviral activity, tying the phenotype to the enzyme's product. Supporting Evidence: PMID:33239446 our data support a model that 25HC suppresses SARS-CoV-2 S protein-mediated fusion, which inhibits virus replication
GO:0001567 cholesterol 25-hydroxylase activity	ISS GO_REF:0000024	ACCEPT	Summary: Core molecular function, inferred by sequence similarity from mouse (Q9Z0F5) and redundant with the direct experimental annotations to the same term. Consistent. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt Catalyzes the formation of 25-hydroxycholesterol from
GO:0035754 B cell chemotaxis	ISS GO_REF:0000024	KEEP AS NON CORE	Summary: Downstream/indirect physiological role inferred by similarity from mouse. Same as the Ensembl IEA to this term: CH25H does not have chemotactic activity itself; its product feeds 7alpha,25-diHC/EBI2-mediated lymphocyte positioning. Non-core. Supporting Evidence: PMID:33239446 25HC is further converted to 7-α, 25-dihydroxycholesterol (7-α, 25-diHC), an oxysterol that functions as a chemoattractant for T cells and B cells
GO:0005829 cytosol	TAS Reactome:R-HSA-191983	MARK AS OVER ANNOTATED	Summary: Mislocalization. This TAS annotation reflects the compartment assigned to a Reactome reaction ("Cholesterol is hydroxylated to 25-hydroxycholesterol"), not the true topology of the enzyme. CH25H is a multi-pass integral ER-membrane protein (three transmembrane helices); it is not a cytosolic protein. The ER membrane annotations are the accurate ones. Supporting Evidence: file:human/CH25H/CH25H-uniprot.txt CC -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane CC {ECO:0000250\|UniProtKB:Q9Z0F5}; Multi-pass membrane protein CC {ECO:0000250\|UniProtKB:Q9Z0F5}.
GO:0006629 lipid metabolic process	TAS PMID:9852097 cDNA cloning of mouse and human cholesterol 25-hydroxylases,...	KEEP AS NON CORE	Summary: Correct but very general. CH25H participates in lipid (sterol/oxysterol) metabolism; the specific processes (cholesterol/oxysterol metabolic process) are annotated separately. Kept as non-core high-level context. Supporting Evidence: PMID:9852097 a potent oxysterol regulator of lipid metabolism
GO:0008395 steroid hydroxylase activity	TAS PMID:9852097 cDNA cloning of mouse and human cholesterol 25-hydroxylases,...	MODIFY	Summary: Correct but overly general: this is the direct parent of GO:0001567 cholesterol 25-hydroxylase activity, which is the specific, experimentally demonstrated activity. Recommend replacing with the specific child term. Proposed replacements: cholesterol 25-hydroxylase activity Supporting Evidence: PMID:9852097 Here, we report the cloning of cholesterol
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome.	KEEP AS NON CORE	Summary: The reported physical interaction is retained as non-core; generic protein binding does not specify the catalytic mechanism. Reason: Physical interaction and catalytic function are distinct claims. The observed interaction does not independently establish a new enzyme activity.

Gene Description

Existing Annotations Review

Core Functions

Cholesterol 25-hydroxylase: an ER-membrane, diiron (non-P450) oxygenase that hydroxylates cholesterol at C-25 to produce the regulatory oxysterol 25-hydroxycholesterol, using molecular oxygen and iron.

Iron cofactor binding for catalysis: CH25H coordinates a diiron center (conserved histidine-box motifs) required for its monooxygenase activity.

Antiviral effector function of the 25-HC product: as an interferon-stimulated gene, CH25H restrains enveloped-virus infection by blocking virus membrane fusion with the host plasma membrane.

References

Deep Research

Falcon

Manual

📚 Additional Documentation

Notes

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