id: F6T000 gene_symbol: CH25H taxon: id: NCBITaxon:9796 label: Equus caballus status: COMPLETE description: Assessment of 3 ProtNLM GO predictions for the selected horse CH25H protein, using mammalian experimental findings and an explicit comparison of the horse sequence. source_documents: - genes/human/CH25H/CH25H-uniprot.txt - genes/HORSE/CH25H/CH25H-bioinformatics/RESULTS.md - projects/PROTNLM_EVALUATION/mammal-benchmark/horse40-predictions.csv predictions: - source_method: ProtNLM2 source_version: UniProt API snapshot 2026-09-08 predicted_term: id: GO:0016491 label: oxidoreductase activity predicted_term_type: GO_MF review: assessment: LSP confidence_score: 2 summary: Cholesterol 25-hydroxylation is a specific oxidoreductase reaction established for cloned human and mouse enzymes in PMID:9852097. The horse protein retains the conserved enzyme sequence and histidine-rich architecture. The prediction is biologically correct but less specific than cholesterol 25-hydroxylase activity already present in horse GOA. Training-set membership is unknown. supported_by: - reference_id: file:human/CH25H/CH25H-uniprot.txt supporting_text: 'CC -!- FUNCTION: Catalyzes the formation of 25-hydroxycholesterol from CC cholesterol, leading to repress cholesterol biosynthetic enzymes CC (PubMed:9852097). Plays a key role in cell positioning and movement in CC lymphoid tissues: 25-hydroxycholesterol is an intermediate in CC biosynthesis of 7-alpha,25-dihydroxycholesterol (7-alpha,25-OHC), an CC oxysterol that acts as a ligand for the G protein-coupled receptor CC GPR183/EBI2, a chemotactic receptor for a number of lymphoid cells (By CC similarity). May play an important role in regulating lipid metabolism CC by synthesizing a corepressor that blocks sterol regulatory element CC binding protein (SREBP) processing (PubMed:9852097). As an interferon- CC stimulated gene, has broad antiviral activities against a wide range of CC enveloped viruses, such as vesicular stomatitis virus (VSV) and SARS CC coronavirus-2 (SARS-CoV-2). Its product, 25-hydroxycholesterol, CC activates the ER-localized enzyme ACAT to induce internalization of CC accessible cholesterol on the plasma membrane and restricts SARS-CoV-2 CC S protein-mediated fusion which inhibits virus replication CC (PubMed:32944968, PubMed:33239446). In testis, production of 25- CC hydroxycholesterol by macrophages plays a role in Leydig cell CC differentiation (By similarity). Required to restrain inflammation in CC macrophages: production of 25-hydroxycholesterol protects macrophages CC from cholesterol overload, thereby preventing mitochondrial DNA release CC and subsequent activation of the AIM2 inflammasome (By similarity). CC {ECO:0000250|UniProtKB:Q4QQV7, ECO:0000250|UniProtKB:Q9Z0F5, CC ECO:0000269|PubMed:32944968, ECO:0000269|PubMed:33239446, CC ECO:0000269|PubMed:9852097}.' - reference_id: file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md supporting_text: The horse sequence F6T000 (270 residues) aligns to human O95992 (272 residues) with 83.33% identity across 270 paired residues. Paired coverage is 99.26% of the human sequence and 100.0% of the horse sequence. - reference_id: PMID:9852097 supporting_text: "Here, we report the cloning of cholesterol \n25-hydroxylase cDNAs from the mouse\ \ and human. The encoded enzymes are polytopic \nmembrane proteins of 298 and 272 amino acids,\ \ respectively, which contain \nclusters of histidine residues that are essential for catalytic\ \ activity. Unlike \nmost other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome\ \ \nP450, but rather it is a member of a small family of enzymes that utilize diiron \ncofactors\ \ to catalyze the hydroxylation of hydrophobic substrates. The \ncholesterol 25-hydroxylase gene\ \ lacks introns, and in the human it is located on \nchromosome 10q23. The murine gene is expressed\ \ at low levels in multiple \ntissues. Expression of cholesterol 25-hydroxylase in transfected\ \ cells reduces \nthe biosynthesis of cholesterol from acetate and suppresses the cleavage of\ \ \nsterol regulatory element binding protein-1 and -2. The data suggest that \ncholesterol 25-hydroxylase\ \ has the capacity to play an important role in \nregulating lipid metabolism by synthesizing\ \ a co-repressor that blocks sterol \nregulatory element binding protein processing and ultimately\ \ leads to inhibition \nof gene transcription." - source_method: ProtNLM2 source_version: UniProt API snapshot 2026-09-08 predicted_term: id: GO:0008610 label: lipid biosynthetic process predicted_term_type: GO_BP review: assessment: CNN confidence_score: 2 summary: CH25H produces the oxysterol 25-hydroxycholesterol from cholesterol. That product-forming reaction supports lipid biosynthesis even though the product also represses cholesterol biosynthesis; inhibition of the latter pathway does not make this broad BP false. The exact target GOA term is present. This does not validate the separate zymosterol or C-4 methylsterol assertions. Training-set membership is unknown. supported_by: - reference_id: file:human/CH25H/CH25H-uniprot.txt supporting_text: 'CC -!- FUNCTION: Catalyzes the formation of 25-hydroxycholesterol from CC cholesterol, leading to repress cholesterol biosynthetic enzymes CC (PubMed:9852097). Plays a key role in cell positioning and movement in CC lymphoid tissues: 25-hydroxycholesterol is an intermediate in CC biosynthesis of 7-alpha,25-dihydroxycholesterol (7-alpha,25-OHC), an CC oxysterol that acts as a ligand for the G protein-coupled receptor CC GPR183/EBI2, a chemotactic receptor for a number of lymphoid cells (By CC similarity). May play an important role in regulating lipid metabolism CC by synthesizing a corepressor that blocks sterol regulatory element CC binding protein (SREBP) processing (PubMed:9852097). As an interferon- CC stimulated gene, has broad antiviral activities against a wide range of CC enveloped viruses, such as vesicular stomatitis virus (VSV) and SARS CC coronavirus-2 (SARS-CoV-2). Its product, 25-hydroxycholesterol, CC activates the ER-localized enzyme ACAT to induce internalization of CC accessible cholesterol on the plasma membrane and restricts SARS-CoV-2 CC S protein-mediated fusion which inhibits virus replication CC (PubMed:32944968, PubMed:33239446). In testis, production of 25- CC hydroxycholesterol by macrophages plays a role in Leydig cell CC differentiation (By similarity). Required to restrain inflammation in CC macrophages: production of 25-hydroxycholesterol protects macrophages CC from cholesterol overload, thereby preventing mitochondrial DNA release CC and subsequent activation of the AIM2 inflammasome (By similarity). CC {ECO:0000250|UniProtKB:Q4QQV7, ECO:0000250|UniProtKB:Q9Z0F5, CC ECO:0000269|PubMed:32944968, ECO:0000269|PubMed:33239446, CC ECO:0000269|PubMed:9852097}.' - reference_id: file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md supporting_text: The horse sequence F6T000 (270 residues) aligns to human O95992 (272 residues) with 83.33% identity across 270 paired residues. Paired coverage is 99.26% of the human sequence and 100.0% of the horse sequence. - reference_id: PMID:9852097 supporting_text: "Here, we report the cloning of cholesterol \n25-hydroxylase cDNAs from the mouse\ \ and human. The encoded enzymes are polytopic \nmembrane proteins of 298 and 272 amino acids,\ \ respectively, which contain \nclusters of histidine residues that are essential for catalytic\ \ activity. Unlike \nmost other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome\ \ \nP450, but rather it is a member of a small family of enzymes that utilize diiron \ncofactors\ \ to catalyze the hydroxylation of hydrophobic substrates. The \ncholesterol 25-hydroxylase gene\ \ lacks introns, and in the human it is located on \nchromosome 10q23. The murine gene is expressed\ \ at low levels in multiple \ntissues. Expression of cholesterol 25-hydroxylase in transfected\ \ cells reduces \nthe biosynthesis of cholesterol from acetate and suppresses the cleavage of\ \ \nsterol regulatory element binding protein-1 and -2. The data suggest that \ncholesterol 25-hydroxylase\ \ has the capacity to play an important role in \nregulating lipid metabolism by synthesizing\ \ a co-repressor that blocks sterol \nregulatory element binding protein processing and ultimately\ \ leads to inhibition \nof gene transcription." - source_method: ProtNLM2 source_version: UniProt API snapshot 2026-09-08 predicted_term: id: GO:0016020 label: membrane predicted_term_type: GO_CC review: assessment: LSP confidence_score: 2 summary: The cloned human and mouse enzymes are polytopic membrane proteins (PMID:9852097). The horse sequence is nearly full length relative to human and retains the membrane-enzyme architecture. Membrane is correct but less informative than the existing horse endoplasmic reticulum membrane annotation. Training-set membership is unknown. supported_by: - reference_id: file:human/CH25H/CH25H-uniprot.txt supporting_text: 'CC -!- FUNCTION: Catalyzes the formation of 25-hydroxycholesterol from CC cholesterol, leading to repress cholesterol biosynthetic enzymes CC (PubMed:9852097). Plays a key role in cell positioning and movement in CC lymphoid tissues: 25-hydroxycholesterol is an intermediate in CC biosynthesis of 7-alpha,25-dihydroxycholesterol (7-alpha,25-OHC), an CC oxysterol that acts as a ligand for the G protein-coupled receptor CC GPR183/EBI2, a chemotactic receptor for a number of lymphoid cells (By CC similarity). May play an important role in regulating lipid metabolism CC by synthesizing a corepressor that blocks sterol regulatory element CC binding protein (SREBP) processing (PubMed:9852097). As an interferon- CC stimulated gene, has broad antiviral activities against a wide range of CC enveloped viruses, such as vesicular stomatitis virus (VSV) and SARS CC coronavirus-2 (SARS-CoV-2). Its product, 25-hydroxycholesterol, CC activates the ER-localized enzyme ACAT to induce internalization of CC accessible cholesterol on the plasma membrane and restricts SARS-CoV-2 CC S protein-mediated fusion which inhibits virus replication CC (PubMed:32944968, PubMed:33239446). In testis, production of 25- CC hydroxycholesterol by macrophages plays a role in Leydig cell CC differentiation (By similarity). Required to restrain inflammation in CC macrophages: production of 25-hydroxycholesterol protects macrophages CC from cholesterol overload, thereby preventing mitochondrial DNA release CC and subsequent activation of the AIM2 inflammasome (By similarity). CC {ECO:0000250|UniProtKB:Q4QQV7, ECO:0000250|UniProtKB:Q9Z0F5, CC ECO:0000269|PubMed:32944968, ECO:0000269|PubMed:33239446, CC ECO:0000269|PubMed:9852097}.' - reference_id: file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md supporting_text: The horse sequence F6T000 (270 residues) aligns to human O95992 (272 residues) with 83.33% identity across 270 paired residues. Paired coverage is 99.26% of the human sequence and 100.0% of the horse sequence. - reference_id: PMID:9852097 supporting_text: "Here, we report the cloning of cholesterol \n25-hydroxylase cDNAs from the mouse\ \ and human. The encoded enzymes are polytopic \nmembrane proteins of 298 and 272 amino acids,\ \ respectively, which contain \nclusters of histidine residues that are essential for catalytic\ \ activity. Unlike \nmost other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome\ \ \nP450, but rather it is a member of a small family of enzymes that utilize diiron \ncofactors\ \ to catalyze the hydroxylation of hydrophobic substrates. The \ncholesterol 25-hydroxylase gene\ \ lacks introns, and in the human it is located on \nchromosome 10q23. The murine gene is expressed\ \ at low levels in multiple \ntissues. Expression of cholesterol 25-hydroxylase in transfected\ \ cells reduces \nthe biosynthesis of cholesterol from acetate and suppresses the cleavage of\ \ \nsterol regulatory element binding protein-1 and -2. The data suggest that \ncholesterol 25-hydroxylase\ \ has the capacity to play an important role in \nregulating lipid metabolism by synthesizing\ \ a co-repressor that blocks sterol \nregulatory element binding protein processing and ultimately\ \ leads to inhibition \nof gene transcription." references: - id: file:human/CH25H/CH25H-uniprot.txt title: UniProt record for human CH25H findings: [] - id: file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md title: "CH25H: horse\u2013human sequence comparison" findings: [] - id: PMID:9852097 title: cDNA cloning of mouse and human cholesterol 25-hydroxylases, polytopic membrane proteins that synthesize a potent oxysterol regulator of lipid metabolism. findings: []