CH25H is a membrane-associated cholesterol 25-hydroxylase that produces the regulatory oxysterol 25-hydroxycholesterol. It belongs to a histidine-rich diiron enzyme family. Its product regulates sterol homeostasis and contributes to mammalian immune-cell positioning and defense against enveloped viruses.
Summary: The characterized CH25H reaction is cholesterol C25 hydroxylation, not removal of the C4 methyl groups during sterol biosynthesis. Shared sterol-enzyme ancestry does not support this substrate-specific reaction.
Reason: The characterized CH25H reaction is cholesterol C25 hydroxylation, not removal of the C4 methyl groups during sterol biosynthesis. Shared sterol-enzyme ancestry does not support this substrate-specific reaction. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: Human and mouse cloning and enzymology identify cholesterol 25-hydroxylase; the horse sequence conserves the enzyme architecture.
Reason: Human and mouse cloning and enzymology identify cholesterol 25-hydroxylase; the horse sequence conserves the enzyme architecture. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: Human and mouse cloning and enzymology identify cholesterol 25-hydroxylase; the horse sequence conserves the enzyme architecture.
Reason: Human and mouse cloning and enzymology identify cholesterol 25-hydroxylase; the horse sequence conserves the enzyme architecture. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: CH25H uses a diiron cofactor coordinated by histidine clusters; the conserved horse architecture supports this property.
Reason: CH25H uses a diiron cofactor coordinated by histidine clusters; the conserved horse architecture supports this property. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: The protein is a polytopic ER-membrane sterol enzyme, consistent with conserved membrane-spanning architecture.
Reason: The protein is a polytopic ER-membrane sterol enzyme, consistent with conserved membrane-spanning architecture. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: Cholesterol is directly hydroxylated to 25-hydroxycholesterol.
Reason: Cholesterol is directly hydroxylated to 25-hydroxycholesterol. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: The hydroxylation position and sterol substrate are known.
Reason: The hydroxylation position and sterol substrate are known. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: Synthesis of the lipid 25-hydroxycholesterol is compatible with lipid biosynthesis even though the product suppresses other lipid-synthesis reactions.
Reason: Synthesis of the lipid 25-hydroxycholesterol is compatible with lipid biosynthesis even though the product suppresses other lipid-synthesis reactions. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: The ER membrane is the more informative established location.
Reason: The ER membrane is the more informative established location. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
CC -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane CC {ECO:0000250|UniProtKB:Q9Z0F5}; Multi-pass membrane protein CC {ECO:0000250|UniProtKB:Q9Z0F5}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
Summary: Interferon induction regulates CH25H expression and antiviral deployment; induction is a regulatory context rather than the chemical function.
Reason: Interferon induction regulates CH25H expression and antiviral deployment; induction is a regulatory context rather than the chemical function. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Summary: The oxysterol product is an intermediate in chemotactic ligand synthesis; the broader mammalian immune-cell positioning role is indirect to the catalytic activity.
Reason: The oxysterol product is an intermediate in chemotactic ligand synthesis; the broader mammalian immune-cell positioning role is indirect to the catalytic activity. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Summary: CH25H forms 25-hydroxycholesterol from cholesterol and is not the C4-demethylation enzyme of the zymosterol biosynthetic route.
Reason: CH25H forms 25-hydroxycholesterol from cholesterol and is not the C4-demethylation enzyme of the zymosterol biosynthetic route. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
GO:0090206 negative regulation of cholesterol metabolic process
Reason: 25-hydroxycholesterol represses cholesterol biosynthetic enzymes, connecting catalysis to feedback regulation. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
GO:1903914 negative regulation of fusion of virus membrane with host plasma membrane
IEA GO_REF:0000107
KEEP AS NON CORE
Summary: The oxysterol can inhibit enveloped-virus fusion; this is a downstream biological effect demonstrated in mammalian systems, not direct action on viral proteins.
Reason: The oxysterol can inhibit enveloped-virus fusion; this is a downstream biological effect demonstrated in mammalian systems, not direct action on viral proteins. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Core Functions
CH25H is a membrane-associated cholesterol 25-hydroxylase that produces the regulatory oxysterol 25-hydroxycholesterol. It belongs to a histidine-rich diiron enzyme family. Its product regulates sterol homeostasis and contributes to mammalian immune-cell positioning and defense against enveloped viruses.
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}.
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md
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.
Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription.
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
Assessment of 3 ProtNLM GO predictions for the selected horse CH25H protein, using mammalian experimental findings and an explicit comparison of the horse sequence.
LSP — Less precise than existing annotation Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: 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.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt: "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}."
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md: "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."
PMID:9852097: "Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription."
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: 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.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt: "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}."
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md: "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."
PMID:9852097: "Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription."
LSP — Less precise than existing annotation Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: 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.
Supporting Evidence:
file:human/CH25H/CH25H-uniprot.txt: "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}."
file:HORSE/CH25H/CH25H-bioinformatics/RESULTS.md: "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."
PMID:9852097: "Here, we report the cloning of cholesterol 25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic membrane proteins of 298 and 272 amino acids, respectively, which contain clusters of histidine residues that are essential for catalytic activity. Unlike most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome P450, but rather it is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on chromosome 10q23. The murine gene is expressed at low levels in multiple tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces the biosynthesis of cholesterol from acetate and suppresses the cleavage of sterol regulatory element binding protein-1 and -2. The data suggest that cholesterol 25-hydroxylase has the capacity to play an important role in regulating lipid metabolism by synthesizing a co-repressor that blocks sterol regulatory element binding protein processing and ultimately leads to inhibition of gene transcription."