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1  structure 1569  species 0  interactions 5602  sequences 76  architectures

Family: Steroid_dh (PF02544)

Summary: 3-oxo-5-alpha-steroid 4-dehydrogenase

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3-oxo-5-alpha-steroid 4-dehydrogenase Provide feedback

This family consists of 3-oxo-5-alpha-steroid 4-dehydrogenases, EC: Also known as Steroid 5-alpha-reductase, the reaction catalysed by this enzyme is: 3-oxo-5-alpha-steroid + acceptor <=> 3-oxo-delta(4)-steroid + reduced acceptor. The Steroid 5-alpha-reductase enzyme is responsible for the formation of dihydrotestosterone, this hormone promotes the differentiation of male external genitalia and the prostate during fetal development [2]. In humans mutations in this enzyme can cause a form of male pseudohermaphorditism in which the external genitalia and prostate fail to develop normally [2]. A related enzyme is also found in plants is Q38944 (DET2) a steroid reductase from Arabidopsis. Mutations in this enzyme cause defects in light-regulated development [1].

Literature references

  1. Li J, Nagpal P, Vitart V, McMorris TC, Chory J; , Science 1996;272:398-401.: A role for brassinosteroids in light-dependent development of Arabidopsis PUBMED:8602526 EPMC:8602526

  2. Jenkins EP, Hsieh CL, Milatovich A, Normington K, Berman DM, Francke U, Russell DW; , Genomics 1991;11:1102-1112.: Characterization and chromosomal mapping of a human steroid 5 alpha-reductase gene and pseudogene and mapping of the mouse homologue. PUBMED:1686016 EPMC:1686016

  3. Andersson S, Berman DM, Jenkins EP, Russell DW; , Nature 1991;354:159-161.: Deletion of steroid 5 alpha-reductase 2 gene in male pseudohermaphroditism. PUBMED:1944596 EPMC:1944596

Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR001104

3-oxo-5-alpha-steroid 4-dehydrogenases, EC catalyse the conversion of 3-oxo-5-alpha-steroid + acceptor to 3-oxo-delta(4)-steroid + reduced acceptor. The steroid 5-alpha-reductase enzyme is responsible for the formation of dihydrotestosterone, this hormone promotes the differentiation of male external genitalia and the prostate during foetal development [ PUBMED:1686016 ]. In humans mutations in this enzyme can cause a form of male pseudohermaphorditism in which the external genitalia and prostate fail to develop normally. A related steroid reductase enzyme, DET2, is found in plants such as Arabidopsis. Mutations in this enzyme cause defects in light-regulated development [ PUBMED:8602526 ]. This domain is present in both type 1 and type 2 [ PUBMED:1944596 ] forms.

This domain is also found in polyprenol reductase (SRD5A3; EC ), which is reduces the alpha-isoprene unit of polyprenol to form dolichol. Dolichol is required for the synthesis of a dolichol-linked monosaccharide and the oligosaccharide precursor used for N-glycosylation [ PUBMED:20637498 ].

Another enzyme with this domain is very-long-chain enoyl-CoA reductase (TECR; EC ), which catalyzes the last of the four reactions of the long-chain fatty acids elongation cycle by reducing the trans-2,3-enoyl-CoA fatty acid intermediate to an acyl-CoA that can be further elongated by entering a new cycle of elongation [ PUBMED:12482854 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan Steroid_dh (CL0115), which has the following description:

This clan includes several enzymes, including steroid dehydrogenases and isoprenylcysteine carboxyl methyltransferase enzymes. These protein contain a varying number of transmembrane regions.

The clan contains the following 6 members:

DUF1295 ERG4_ERG24 ICMT NnrU PEMT Steroid_dh


We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

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Curation View help on the curation process

Seed source: Pfam-B_1713 (release 5.4)
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Bashton M , Bateman A
Number in seed: 10
Number in full: 5602
Average length of the domain: 142.20 aa
Average identity of full alignment: 25 %
Average coverage of the sequence by the domain: 48.75 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 22.6 22.6
Trusted cut-off 22.6 22.6
Noise cut-off 22.5 22.5
Model length: 150
Family (HMM) version: 18
Download: download the raw HMM for this family

Species distribution

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Steroid_dh domain has been found. There are 1 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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