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Entry version 128 (23 Feb 2022)
Sequence version 1 (01 May 2000)
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C-4 methylsterol oxidase erg25



Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast)
Reviewed-Annotation score:

Annotation score:4 out of 5

<p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB entry or proteome. This score <strong>cannot</strong> be used as a measure of the accuracy of the annotation as we cannot define the 'correct annotation' for any given protein.<p><a href='/help/annotation_score' target='_top'>More...</a></p>
-Experimental evidence at transcript leveli <p>This indicates the type of evidence that supports the existence of the protein. Note that the 'protein existence' evidence does not give information on the accuracy or correctness of the sequence(s) displayed.<p><a href='/help/protein_existence' target='_top'>More...</a></p>

<p>This section provides any useful information about the protein, mostly biological knowledge.<p><a href='/help/function_section' target='_top'>More...</a></p>Functioni

C-4 methylsterol oxidase; part of the third module of ergosterol biosynthesis pathway that includes by the late steps of the pathway (PubMed:8474436).

The third module or late pathway involves the ergosterol synthesis itself through consecutive reactions that mainly occur in the endoplasmic reticulum (ER) membrane (By similarity).

Firstly, the squalene synthase erg9 catalyzes the condensation of 2 farnesyl pyrophosphate moieties to form squalene, which is the precursor of all steroids (PubMed:8474436).

Secondly, squalene is converted into lanosterol by the consecutive action of the squalene epoxidase erg1 and the lanosterol synthase erg7 (PubMed:8604986, PubMed:33223513).

The lanosterol 14-alpha-demethylase erg11/cyp1 catalyzes C14-demethylation of lanosterol to produce 4,4'-dimethyl cholesta-8,14,24-triene-3-beta-ol (PubMed:27585850).

In the next steps, a complex process involving various demethylation, reduction and desaturation reactions catalyzed by the C-14 reductase erg24 and the C-4 demethylation complex erg25-erg26-erg27 leads to the production of zymosterol (By similarity).

Erg28 likely functions in the C-4 demethylation complex reaction by tethering erg26 and Erg27 to the endoplasmic reticulum or to facilitate interaction between these proteins (Probable). Then, the sterol 24-C-methyltransferase erg6 catalyzes the methyl transfer from S-adenosyl-methionine to the C-24 of zymosterol to form fecosterol (PubMed:18310029).

The C-8 sterol isomerase erg2 catalyzes the reaction which results in unsaturation at C-7 in the B ring of sterols and thus converts fecosterol to episterol (PubMed:18310029).

The sterol-C5-desaturases erg31 and erg32 then catalyze the introduction of a C-5 double bond in the B ring to produce 5-dehydroepisterol (PubMed:18310029).

The C-22 sterol desaturase erg5 further converts 5-dehydroepisterol into ergosta-5,7,22,24(28)-tetraen-3beta-ol by forming the C-22(23) double bond in the sterol side chain (PubMed:18310029).

Finally, ergosta-5,7,22,24(28)-tetraen-3beta-ol is substrate of the C-24(28) sterol reductase erg4 to produce ergosterol (PubMed:18310029).

In the genus Schizosaccharomyces, a second route exists between lanosterol and fecosterol, via the methylation of lanosterol to eburicol by erg6, followed by C14-demethylation by erg11/cyp1 and C4-demethylation by the demethylation complex erg25-erg26-erg27 (PubMed:8586261).

By similarity1 Publication6 Publications


In Aspergillus, the biosynthesis pathway of the sterol precursors leading to the prevalent sterol ergosterol differs from yeast. The ringsystem of lanosterol in S.cerevisiae is firstly demethylised in three enzymatic steps leading to the intermediate zymosterol and secondly a methyl group is added to zymosterol by the sterol 24-C-methyltransferase to form fecosterol. In Aspergillus, lanosterol is firstly transmethylated by the sterol 24-C-methyltransferase leading to the intermediate eburicol and secondly demethylated in three steps to form fecosterol. In the genus Schizosaccharomyces, 2 routes exist from lanosterol to erposterol: the classical one via zymosterol and the second one via the formation of eburicol followed by demethylation.1 Publication

<p>This subsection of the <a href="">Function</a> section describes the catalytic activity of an enzyme, i.e. a chemical reaction that the enzyme catalyzes.<p><a href='/help/catalytic_activity' target='_top'>More...</a></p>Catalytic activityi

<p>This subsection of the 'Function' section provides information relevant to cofactors. A cofactor is any non-protein substance required for a protein to be catalytically active. Some cofactors are inorganic, such as the metal atoms zinc, iron, and copper in various oxidation states. Others, such as most vitamins, are organic.<p><a href='/help/cofactor' target='_top'>More...</a></p>Cofactori

Fe cationBy similarity

<p>This subsection of the <a href="">'Function'</a> section describes the metabolic pathway(s) associated with a protein.<p><a href='/help/pathway' target='_top'>More...</a></p>Pathwayi: zymosterol biosynthesis

This protein is involved in step 3 of the subpathway that synthesizes zymosterol from lanosterol.By similarity This subpathway is part of the pathway zymosterol biosynthesis, which is itself part of Steroid biosynthesis.
View all proteins of this organism that are known to be involved in the subpathway that synthesizes zymosterol from lanosterol, the pathway zymosterol biosynthesis and in Steroid biosynthesis.

Pathwayi: ergosterol biosynthesis

This protein is involved in the pathway ergosterol biosynthesis, which is part of Steroid metabolism.By similarity
View all proteins of this organism that are known to be involved in the pathway ergosterol biosynthesis and in Steroid metabolism.

<p>The <a href="">Gene Ontology (GO)</a> project provides a set of hierarchical controlled vocabulary split into 3 categories:<p><a href='/help/gene_ontology' target='_top'>More...</a></p>GO - Molecular functioni

GO - Biological processi

<p>UniProtKB Keywords constitute a <a href="">controlled vocabulary</a> with a hierarchical structure. Keywords summarise the content of a UniProtKB entry and facilitate the search for proteins of interest.<p><a href='/help/keywords' target='_top'>More...</a></p>Keywordsi

Molecular functionOxidoreductase
Biological processLipid biosynthesis, Lipid metabolism, Steroid biosynthesis, Steroid metabolism, Sterol biosynthesis, Sterol metabolism
LigandIron, NAD

Enzyme and pathway databases

Reactome - a knowledgebase of biological pathways and processes

R-SPO-191273, Cholesterol biosynthesis
R-SPO-192105, Synthesis of bile acids and bile salts

UniPathway: a resource for the exploration and annotation of metabolic pathways


<p>This section provides information about the protein and gene name(s) and synonym(s) and about the organism that is the source of the protein sequence.<p><a href='/help/names_and_taxonomy_section' target='_top'>More...</a></p>Names & Taxonomyi

<p>This subsection of the <a href="">Names and taxonomy</a> section provides an exhaustive list of all names of the protein, from commonly used to obsolete, to allow unambiguous identification of a protein.<p><a href='/help/protein_names' target='_top'>More...</a></p>Protein namesi
Recommended name:
C-4 methylsterol oxidase erg251 Publication (EC:1.14.18.-By similarity)
Alternative name(s):
Ergosterol biosynthetic protein 25By similarity
Sterol-C4-methyl oxidase erg25By similarity
Short name:
SMOBy similarity
<p>This subsection of the <a href="">Names and taxonomy</a> section indicates the name(s) of the gene(s) that code for the protein sequence(s) described in the entry. Four distinct tokens exist: 'Name', 'Synonyms', 'Ordered locus names' and 'ORF names'.<p><a href='/help/gene_name' target='_top'>More...</a></p>Gene namesi
Name:erg251 Publication
ORF Names:SPAC630.08c
<p>This subsection of the <a href="">Names and taxonomy</a> section provides information on the name(s) of the organism that is the source of the protein sequence.<p><a href='/help/organism-name' target='_top'>More...</a></p>OrganismiSchizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast)
<p>This subsection of the <a href="">Names and taxonomy</a> section shows the unique identifier assigned by the NCBI to the source organism of the protein. This is known as the 'taxonomic identifier' or 'taxid'.<p><a href='/help/taxonomic_identifier' target='_top'>More...</a></p>Taxonomic identifieri284812 [NCBI]
<p>This subsection of the <a href="">Names and taxonomy</a> section contains the taxonomic hierarchical classification lineage of the source organism. It lists the nodes as they appear top-down in the taxonomic tree, with the more general grouping listed first.<p><a href='/help/taxonomic_lineage' target='_top'>More...</a></p>Taxonomic lineageiEukaryotaFungiDikaryaAscomycotaTaphrinomycotinaSchizosaccharomycetesSchizosaccharomycetalesSchizosaccharomycetaceaeSchizosaccharomyces
<p>This subsection of the <a href="">Names and taxonomy</a> section is present for entries that are part of a <a href="">proteome</a>, i.e. of a set of proteins thought to be expressed by organisms whose genomes have been completely sequenced.<p><a href='/help/proteomes_manual' target='_top'>More...</a></p>Proteomesi
  • UP000002485 <p>A UniProt <a href="">proteome</a> can consist of several components.<br></br>The component name refers to the genomic component encoding a set of proteins.<p><a href='/help/proteome_component' target='_top'>More...</a></p> Componenti: Chromosome I

Organism-specific databases

Schizosaccharomyces pombe database

SPAC630.08c, erg25

Eukaryotic Pathogen, Vector and Host Database Resources


<p>This section provides information on the location and the topology of the mature protein in the cell.<p><a href='/help/subcellular_location_section' target='_top'>More...</a></p>Subcellular locationi


Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the <a href="">'Subcellular location'</a> section describes the extent of a membrane-spanning region of the protein. It denotes the presence of both alpha-helical transmembrane regions and the membrane spanning regions of beta-barrel transmembrane proteins.<p><a href='/help/transmem' target='_top'>More...</a></p>Transmembranei186 – 206HelicalSequence analysisAdd BLAST21

Keywords - Cellular componenti

Endoplasmic reticulum, Membrane

<p>This section describes post-translational modifications (PTMs) and/or processing events.<p><a href='/help/ptm_processing_section' target='_top'>More...</a></p>PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'PTM / Processing' section describes the extent of a polypeptide chain in the mature protein following processing or proteolytic cleavage.<p><a href='/help/chain' target='_top'>More...</a></p>ChainiPRO_00001170381 – 300C-4 methylsterol oxidase erg25Add BLAST300

Proteomic databases

MaxQB - The MaxQuant DataBase


PaxDb, a database of protein abundance averages across all three domains of life


<p>This section provides information on the expression of a gene at the mRNA or protein level in cells or in tissues of multicellular organisms.<p><a href='/help/expression_section' target='_top'>More...</a></p>Expressioni

<p>This subsection of the 'Expression' section reports the experimentally proven effects of inducers and repressors (usually chemical compounds or environmental factors) on the level of protein (or mRNA) expression (up-regulation, down-regulation, constitutive expression).<p><a href='/help/induction' target='_top'>More...</a></p>Inductioni

Expression is highly up-regulated under low oxygen and low sterol conditions in a sre1- and scp1-dependent manner.1 Publication

<p>This section provides information on the quaternary structure of a protein and on interaction(s) with other proteins or protein complexes.<p><a href='/help/interaction_section' target='_top'>More...</a></p>Interactioni

<p>This subsection of the <a href="">'Interaction'</a> section provides information about the protein quaternary structure and interaction(s) with other proteins or protein complexes (with the exception of physiological receptor-ligand interactions which are annotated in the <a href="">'Function'</a> section).<p><a href='/help/subunit_structure' target='_top'>More...</a></p>Subunit structurei

Heterotetramer of erg25, erg26, erg27 and erg28 (By similarity). Erg28 acts as a scaffold to tether erg27 and other 4,4-demethylation-related enzymes, forming a demethylation enzyme complex, in the endoplasmic reticulum (By similarity).

By similarity

Protein-protein interaction databases

STRING: functional protein association networks


<p>This section provides information on the tertiary and secondary structure of a protein.<p><a href='/help/structure_section' target='_top'>More...</a></p>Structurei

<p>This section provides information on sequence similarities with other proteins and the domain(s) present in a protein.<p><a href='/help/family_and_domains_section' target='_top'>More...</a></p>Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the <a href="">Family and Domains</a> section describes the position and type of a domain, which is defined as a specific combination of secondary structures organized into a characteristic three-dimensional structure or fold.<p><a href='/help/domain' target='_top'>More...</a></p>Domaini140 – 276Fatty acid hydroxylaseSequence analysisAdd BLAST137


Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'Family and Domains' section describes a short (usually not more than 20 amino acids) conserved sequence motif of biological significance.<p><a href='/help/motif' target='_top'>More...</a></p>Motifi154 – 158Histidine box-15
Motifi167 – 171Histidine box-25
Motifi251 – 257Histidine box-37

<p>This subsection of the 'Family and domains' section provides general information on the biological role of a domain. The term 'domain' is intended here in its wide acceptation, it may be a structural domain, a transmembrane region or a functional domain. Several domains are described in this subsection.<p><a href='/help/domain_cc' target='_top'>More...</a></p>Domaini

The histidine box domains may contain the active site and/or be involved in metal ion binding.By similarity

<p>This subsection of the 'Family and domains' section provides information about the sequence similarity with other proteins.<p><a href='/help/sequence_similarities' target='_top'>More...</a></p>Sequence similaritiesi

Belongs to the sterol desaturase family.By similarity

Keywords - Domaini

Transmembrane, Transmembrane helix

Phylogenomic databases

evolutionary genealogy of genes: Non-supervised Orthologous Groups

KOG0873, Eukaryota

The HOGENOM Database of Homologous Genes from Fully Sequenced Organisms


InParanoid: Eukaryotic Ortholog Groups


Identification of Orthologs from Complete Genome Data


Database for complete collections of gene phylogenies


Family and domain databases

Integrated resource of protein families, domains and functional sites

View protein in InterPro
IPR006694, Fatty_acid_hydroxylase

Pfam protein domain database

View protein in Pfam
PF04116, FA_hydroxylase, 1 hit

<p>This section displays by default the canonical protein sequence and upon request all isoforms described in the entry. It also includes information pertinent to the sequence(s), including <a href="">length</a> and <a href="">molecular weight</a>. The information is filed in different subsections. The current subsections and their content are listed below:<p><a href='/help/sequences_section' target='_top'>More...</a></p>Sequencei

<p>This subsection of the <a href="">Sequence</a> section indicates if the <a href="">canonical sequence</a> displayed by default in the entry is complete or not.<p><a href='/help/sequence_status' target='_top'>More...</a></p>Sequence statusi: Complete.

Q9UUH4-1 [UniParc]FASTAAdd to basket
« Hide
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60 70 80 90 100
110 120 130 140 150
160 170 180 190 200
210 220 230 240 250
260 270 280 290 300
Mass (Da):35,803
Last modified:May 1, 2000 - v1
<p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.</p> <p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.</p> <p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).</p> <p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x<sup>64</sup> + x<sup>4</sup> + x<sup>3</sup> + x + 1. The algorithm is described in the ISO 3309 standard. </p> <p class="publication">Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.<br /> <strong>Cyclic redundancy and other checksums</strong><br /> <a href="">Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993)</a>)</p> Checksum:iAA8C2603D35DF331

Sequence databases

Select the link destinations:

EMBL nucleotide sequence database


GenBank nucleotide sequence database


DNA Data Bank of Japan; a nucleotide sequence database

Links Updated
CU329670 Genomic DNA Translation: CAB52730.1

Protein sequence database of the Protein Information Resource


NCBI Reference Sequences

NP_592903.1, NM_001018303.2

Genome annotation databases

Ensembl fungal genome annotation project

SPAC630.08c.1; SPAC630.08c.1:pep; SPAC630.08c

Database of genes from NCBI RefSeq genomes


KEGG: Kyoto Encyclopedia of Genes and Genomes


<p>This section provides links to proteins that are similar to the protein sequence(s) described in this entry at different levels of sequence identity thresholds (100%, 90% and 50%) based on their membership in UniProt Reference Clusters (<a href="">UniRef</a>).<p><a href='/help/similar_proteins_section' target='_top'>More...</a></p>Similar proteinsi

<p>This section is used to point to information related to entries and found in data collections other than UniProtKB.<p><a href='/help/cross_references_section' target='_top'>More...</a></p>Cross-referencesi

Sequence databases

Select the link destinations:
Links Updated
CU329670 Genomic DNA Translation: CAB52730.1
RefSeqiNP_592903.1, NM_001018303.2

3D structure databases

Database of comparative protein structure models


SWISS-MODEL Interactive Workspace

Submit a new modelling project...

Protein-protein interaction databases


Proteomic databases


Genome annotation databases

EnsemblFungiiSPAC630.08c.1; SPAC630.08c.1:pep; SPAC630.08c

Organism-specific databases

PomBaseiSPAC630.08c, erg25

Phylogenomic databases

eggNOGiKOG0873, Eukaryota

Enzyme and pathway databases

ReactomeiR-SPO-191273, Cholesterol biosynthesis
R-SPO-192105, Synthesis of bile acids and bile salts

Miscellaneous databases

Protein Ontology


Family and domain databases

InterProiView protein in InterPro
IPR006694, Fatty_acid_hydroxylase
PfamiView protein in Pfam
PF04116, FA_hydroxylase, 1 hit

MobiDB: a database of protein disorder and mobility annotations


<p>This section provides general information on the entry.<p><a href='/help/entry_information_section' target='_top'>More...</a></p>Entry informationi

<p>This subsection of the 'Entry information' section provides a mnemonic identifier for a UniProtKB entry, but it is not a stable identifier. Each reviewed entry is assigned a unique entry name upon integration into UniProtKB/Swiss-Prot.<p><a href='/help/entry_name' target='_top'>More...</a></p>Entry nameiERG25_SCHPO
<p>This subsection of the 'Entry information' section provides one or more accession number(s). These are stable identifiers and should be used to cite UniProtKB entries. Upon integration into UniProtKB, each entry is assigned a unique accession number, which is called 'Primary (citable) accession number'.<p><a href='/help/accession_numbers' target='_top'>More...</a></p>AccessioniPrimary (citable) accession number: Q9UUH4
<p>This subsection of the 'Entry information' section shows the date of integration of the entry into UniProtKB, the date of the last sequence update and the date of the last annotation modification ('Last modified'). The version number for both the entry and the <a href="">canonical sequence</a> are also displayed.<p><a href='/help/entry_history' target='_top'>More...</a></p>Entry historyiIntegrated into UniProtKB/Swiss-Prot: February 22, 2003
Last sequence update: May 1, 2000
Last modified: February 23, 2022
This is version 128 of the entry and version 1 of the sequence. See complete history.
<p>This subsection of the 'Entry information' section indicates whether the entry has been manually annotated and reviewed by UniProtKB curators or not, in other words, if the entry belongs to the Swiss-Prot section of UniProtKB (<strong>reviewed</strong>) or to the computer-annotated TrEMBL section (<strong>unreviewed</strong>).<p><a href='/help/entry_status' target='_top'>More...</a></p>Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programFungal Protein Annotation Program

<p>This section contains any relevant information that doesn't fit in any other defined sections<p><a href='/help/miscellaneous_section' target='_top'>More...</a></p>Miscellaneousi

Keywords - Technical termi

Reference proteome


  1. Schizosaccharomyces pombe
    Schizosaccharomyces pombe: entries and gene names
  2. PATHWAY comments
    Index of metabolic and biosynthesis pathways
  3. SIMILARITY comments
    Index of protein domains and families
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