Summary

NADH ubiquinone oxidoreductase, 20 Kd subunit

No Pfam abstract.

Literature references

Walker JE; , Q Rev Biophys 1992;25:253-324.: The NADH:ubiquinone oxidoreductase (complex I) of respiratory chains. PUBMED:1470679
Peterson GC, Souza AE, Parsons M; , Mol Biochem Parasitol 1993;58:63-70.: Characterization of a Trypanosoma brucei nuclear gene encoding a protein homologous to a subunit of bovine NADH:ubiquinone oxidoreductase (complex I). PUBMED:8459836
Arizmendi JM, Runswick MJ, Skehel JM, Walker JE; , FEBS Lett 1992;301:237-242.: NADH: ubiquinone oxidoreductase from bovine heart mitochondria. A fourth nuclear encoded subunit with a homologue encoded in chloroplast genomes. PUBMED:1577158

InterPro entry IPR006137

Among the many polypeptide subunits that make up complex I, there is one with a molecular weight of 20 kDa (in mammals) PUBMED:1577158, which is a component of the iron-sulphur (IP) fragment of the enzyme. It seems to bind a 4Fe-4S iron-sulphur cluster. The 20 kDa subunit has been found to be nuclear encoded, as a precursor form with a transit peptide in mammals, and in Neurospora crassa. It is and chloroplast encoded in various higher plants (gene ndhK or psbG).

NADH:ubiquinone oxidoreductase (complex I) () is a respiratory-chain enzyme that catalyses the transfer of two electrons from NADH to ubiquinone in a reaction that is associated with proton translocation across the membrane (NADH + ubiquinone = NAD+ + ubiquinol) PUBMED:1470679. Complex I is a major source of reactive oxygen species (ROS) that are predominantly formed by electron transfer from FMNH(2). Complex I is found in bacteria, cyanobacteria (as a NADH-plastoquinone oxidoreductase), archaea PUBMED:10940377, mitochondira, and in the hydrogenosome, a mitochondria-derived organelle. In general, the bacterial complex consists of 14 different subunits, while the mitochondrial complex contains homologues to these subunits in addition to approximately 31 additional proteins PUBMED:18394423. Mitochondrial complex I, which is located in the inner mitochondrial membrane, is the largest multimeric respiratory enzyme in the mitochondria, consisting of more than 40 subunits, one FMN co-factor and eight FeS clusters PUBMED:18563446. The assembly of mitochondrial complex I is an intricate process that requires the cooperation of the nuclear and mitochondrial genomes PUBMED:18563446, PUBMED:17854760. Mitochondrial complex I can cycle between active and deactive forms that can be distinguished by the reactivity towards divalent cations and thiol-reactive agents. All redox prosthetic groups reside in the peripheral arm of the L-shaped structure. The NADH oxidation domain harbouring the FMN cofactor is connected via a chain of iron-sulphur clusters to the ubiquinone reduction site that is located in a large pocket formed by the PSST and 49kDa subunits of complex I PUBMED:18982432.

Gene Ontology

Molecular function	4 iron, 4 sulfur cluster binding (GO:0051539)
	quinone binding (GO:0048038)
	NADH dehydrogenase (ubiquinone) activity (GO:0008137)

External database links

HOMSTRAD:	oxidored_q6
PANDIT:	PF01058
PROSITE:	PDOC00858
SCOP:	1frf
SYSTERS:	Oxidored_q6
Transporter classification:	3.D.1 3.D.7 3.D.9

Domain organisation

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

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Alignments

There are various ways to view or download the sequence alignments that we store. You can use a sequence viewer to look at either the seed or full alignment for the family, or you can look at a plain text version of the sequence in a variety of different formats. More...

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Alignment:	Seed (169) Full (2764) NCBI (4166) Metagenomics (2053)
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Formatting options

Alignment:	Seed (169) Full (2764)
Format:
Order:	Tree Alphabetical
Sequence:	Inserts lower case All upper case
Gaps:
Download/view:	Download View

Download options

Very large alignments can often cause problems for the formatting tool above. If you find that downloading or viewing a large alignment is problematic, you can also download a gzip-compressed, Stockholm-format file containing the seed or full alignment for this family.

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

The main seed and full alignments are generated using sequences from the UniProt sequence database. However, we also generate alignments using sequences from the NCBI sequence database and the "metaseq" metagenomics dataset.

You can view alignments from these two additional datasets using the form above, or you can download alignments of NCBI or metagenomics sequences, as gzip-compressed files.

Pfam alignments:	Seed (169) Full (2764) NCBI (4166) Metagenomics (2053)
Full length sequences	Full-sequences (2764)

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER2.

HMM logo

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...

Trees

This page displays the phylogenetic tree for this family. 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 or full alignments.

Note: You can also download the data files for the seed, full, NCBI or metagenomics trees.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation

Seed source:

Pfam-B_1345 (release 3.0)

Previous IDs:

oxidored_q6;

Type:

Family

Author:

Finn RD, Bateman A

Number in seed:

169

Number in full:

2764

Average length of the domain:

123.00 aa

Average identity of full alignment:

34 %

Average coverage of the sequence by the domain:

50.65 %

HMM information

HMM build commands:

build method: hmmbuild -o /dev/null HMM SEED

search method: hmmsearch -Z 9421015 -E 1000 HMM pfamseq

Model details:

Parameter	Sequence	Domain
Gathering cut-off	21.1	21.1
Trusted cut-off	21.6	21.6
Noise cut-off	18.4	20.2

Model length:

131

Family (HMM) version:

15

Download:

download the raw HMM for this family

Species distribution

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The tree shows the occurrence of this domain across different species. More...

Species trees

We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.

Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.

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Interactive tree

For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.

We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.

Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.

We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.

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Interactions

There is 1 interaction for this family. More...

NiFeSe_Hases

Structures

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 Oxidored_q6 domain has been found.

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Family: Oxidored_q6 (PF01058)

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