Summary: DNA-directed RNA polymerase III subunit Rpc31
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DNA-directed RNA polymerase III subunit Rpc31 Provide feedback
RNA polymerase III contains seventeen subunits in yeasts and in human cells. Twelve of these are akin to RNA polymerase I or II and the other five are RNA pol III-specific, and form the functionally distinct groups (i) Rpc31-Rpc34-Rpc82, and (ii) Rpc37-Rpc53. Rpc31, Rpc34 and Rpc82 form a cluster of enzyme-specific subunits that contribute to transcription initiation in S.cerevisiae and H.sapiens. There is evidence that these subunits are anchored at or near the N-terminal Zn-fold of Rpc1, itself prolonged by a highly conserved but RNA polymerase III-specific domain .
Proshkina GM, Shematorova EK, Proshkin SA, Zaros C, Thuriaux P, Shpakovski GV; , Nucleic Acids Res. 2006;34:3615-3624.: Ancient origin, functional conservation and fast evolution of DNA-dependent RNA polymerase III. PUBMED:16877568 EPMC:16877568
Internal database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR024661
DNA-directed RNA polymerases EC (also known as DNA-dependent RNA polymerases) are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. In eukaryotes, there are three different forms of DNA-directed RNA polymerases transcribing different sets of genes. Most RNA polymerases are multimeric enzymes and are composed of a variable number of subunits. The core RNA polymerase complex consists of five subunits (two alpha, one beta, one beta-prime and one omega) and is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme [ PUBMED:3052291 ]. The core RNA polymerase complex forms a "crab claw"-like structure with an internal channel running along the full length [ PUBMED:10499798 ]. The key functional sites of the enzyme, as defined by mutational and cross-linking analysis, are located on the inner wall of this channel.
RNA synthesis follows after the attachment of RNA polymerase to a specific site, the promoter, on the template DNA strand. The RNA synthesis process continues until a termination sequence is reached. The RNA product, which is synthesised in the 5' to 3' direction, is known as the primary transcript.
Eukaryotic nuclei contain three distinct types of RNA polymerases that differ in the RNA they synthesise:
- RNA polymerase I: located in the nucleoli, synthesises precursors of most ribosomal RNAs.
- RNA polymerase II: occurs in the nucleoplasm, synthesises mRNA precursors.
- RNA polymerase III: also occurs in the nucleoplasm, synthesises the precursors of 5S ribosomal RNA, the tRNAs, and a variety of other small nuclear and cytosolic RNAs.
Eukaryotic cells are also known to contain separate mitochondrial and chloroplast RNA polymerases. Eukaryotic RNA polymerases, whose molecular masses vary in size from 500 to 700kDa, contain two non-identical large (>100kDa) subunits and an array of up to 12 different small (less than 50kDa) subunits.
RNA polymerase III contains seventeen subunits in yeasts and in human cells. Twelve of these are akin to RNA polymerase I or II and the other five are RNA polymerase III-specific, and form the functionally distinct groups: (i) Rpc31-Rpc34-Rpc82, and (ii) Rpc37-Rpc53. Rpc31, Rpc34 and Rpc82 form a cluster of enzyme-specific subunits that contribute to transcription initiation in Saccharomyces cerevisiae and Homo sapiens. There is evidence that these subunits are anchored at or near the N-terminal Zn-fold of Rpc1, itself prolonged by a highly conserved but RNA polymerase III-specific domain [ PUBMED:16877568 ].
This entry represents the Rpc31 subunit. It is also known as RPC7 or RPC32 [ PUBMED:18487626 ].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Biological process||transcription by RNA polymerase III (GO:0006383)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
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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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|Seed source:||Pfam-B_203281 (release 23.0)|
|Author:||Wood V , Coggill P|
|Number in seed:||89|
|Number in full:||1674|
|Average length of the domain:||179.70 aa|
|Average identity of full alignment:||24 %|
|Average coverage of the sequence by the domain:||76.65 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||11|
|Download:||download the raw HMM for this family|
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How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
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Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
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The tree shows the occurrence of this domain across different species. More...
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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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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 RNA_pol_3_Rpc31 domain has been found. There are 24 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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AlphaFold Structure Predictions
The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.