Summary: APOBEC-like N-terminal domain
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APOBEC Edit Wikipedia article
|APOBEC-like N-terminal domain|
|APOBEC-like C-terminal domain|
APOBEC ("apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like") is a family of evolutionarily conserved cytidine deaminases.
A mechanism of generating protein diversity is mRNA editing. Members of this family are C-to-U editing enzymes. The N-terminal domain of APOBEC like proteins is the catalytic domain, while the C-terminal domain is a pseudocatalytic domain. More specifically, the catalytic domain is a zinc dependent cytidine deaminase domain and is essential for cytidine deamination. RNA editing by APOBEC-1 requires homodimerisation and this complex interacts with RNA binding proteins to form the editosome.
Human genes encoding members of the APOBEC protein family include:
- APOBEC3D ("APOBEC3E" now refers to this)
- Activation-induced (cytidine) deaminase (AID)
- doi:10.1038/nature05492. PMID 17187054.; rendered using PyMOL. ; Prochnow, C.; Bransteitter, R.; Klein, M.G.; Goodman, M.F.; Chen, X.S.; functional implications for the deaminase AID. (2007). "The APOBEC-2 crystal structure". Nature. 445 (7126): 447â€“451.
- Wedekind JE, Dance GS, Sowden MP, Smith HC (April 2003). "Messenger RNA editing in mammals: new members of the APOBEC family seeking roles in the family business". Trends Genet. 19 (4): 207â€“16. doi:10.1016/S0168-9525(03)00054-4. PMID 12683974.
- "Unexpected DNA-Binding Mechanism Suggests Ways to Block Enzyme Activity in Cancer". Dec 2016.
Based on ("Structural Basis for Targeted DNA Cytosine Deamination and Mutagenesis by APOBEC3A and APOBEC3B") online in Nature Structural and Molecular Biology.
- Jaguva Vasudevan, AA; Smits SH; HÃ¶ppner A; HÃ¤ussinger D; Koenig BW; MÃ¼nk C. (June 2013). "Structural features of antiviral DNA cytidine deaminases" (PDF). Biol. Chem. 394 (11): 1357â€“1370. doi:10.1515/hsz-2013-0165. PMID 23787464.
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APOBEC-like N-terminal domain Provide feedback
A mechanism of generating protein diversity is mRNA editing. Members of this family are C-to-U editing enzymes. The N-terminal domain of APOBEC-1 like proteins is the catalytic domain, while the C-terminal domain is a pseudocatalyitc domain. More specifically, the catalytic domain is a zinc dependent deaminases domain and is essential for cytidine deamination.APOBEC-3 like members contain two copies of this domain. RNA editing by APOBEC-1 requires homodimerisation and this complex interacts with RNA binding proteins to from the editosome  (and references therein). This family also includes the functionally homologous activation induced deaminase (AID), which is essential for the development of antibody diversity in B lymphocytes, and the sea lamprey PmCDA1 and PmCDA2, which are predicted to play an AID-like role in the adaptive immune response of jawless vertebrates . Divergent members of this family are present in various eukaryotes such as Nematostella, C. elegans, Micromonas and Emiliania, and prokaryotes such as Wolbachia and Pseudomonas brassicacearum .
Wedekind JE, Dance GS, Sowden MP, Smith HC; , Trends Genet 2003;19:207-216.: Messenger RNA editing in mammals: new members of the APOBEC family seeking roles in the family business. PUBMED:12683974 EPMC:12683974
Rogozin IB, Iyer LM, Liang L, Glazko GV, Liston VG, Pavlov YI, Aravind L, Pancer Z;, Nat Immunol. 2007;8:647-656.: Evolution and diversification of lamprey antigen receptors: evidence for involvement of an AID-APOBEC family cytosine deaminase. PUBMED:17468760 EPMC:17468760
Iyer LM, Zhang D, Rogozin IB, Aravind L;, Nucleic Acids Res. 2011; [Epub ahead of print]: Evolution of the deaminase fold and multiple origins of eukaryotic editing and mutagenic nucleic acid deaminases from bacterial toxin systems. PUBMED:21890906 EPMC:21890906
Internal database links
|SCOOP:||AID APOBEC1 APOBEC2 APOBEC3 APOBEC4 APOBEC4_like APOBEC_C Bd3614-deam dCMP_cyt_deam_1 Inv-AAD MafB19-deam NAD1 NAD2 SNAD4 Toxin-deaminase|
|Similarity to PfamA using HHSearch:||APOBEC_C SNAD4 APOBEC1 APOBEC3 APOBEC2 APOBEC4_like APOBEC4 NAD1 NAD2|
This tab holds annotation information from the InterPro database.
InterPro entry IPR013158
This domain is found at the N terminus of the Apolipoprotein B mRNA editing enzyme. Apobec-1 catalyzes C to U editing of apolipoprotein B (apoB) mRNA in the mammalian intestine.
The N-terminal domain of APOBEC-1 like proteins is the catalytic domain, while the C-terminal domain is a pseudocatalyitc domain. More specifically, the catalytic domain is a zinc dependent deaminases domain and is essential for cytidine deamination. APOBEC-3 like members contain two copies of this domain. This family also includes the functionally homologous activation induced deaminase, which is essential for the development of antibody diversity in B lymphocytes. RNA editing by APOBEC-1 requires homodimerisation and this complex interacts with RNA binding proteins to from the editosome [ PUBMED:12683974 ] (and references therein).
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds, in cyclic amidines (GO:0016814)|
|zinc ion binding (GO:0008270)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
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Gladomain, followed by two consecutive
EGFdomains, and finally a single
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This clan contains both free nucleotide and nucleic acid deaminases that act on adenosine, cytosine, guanine and cytidine, and are collectively known as the deaminase superfamily. The conserved fold consists of a three-layered alpha/beta/alpha structure with 3 helices and 4 strands in the 2134 order [1,2].This superfamily is further divided into two major divisions based on the presence of a helix (helix-4) that renders the terminal strands (strands 4 and 5) either parallel to each other in its presence, or anti-parallel in its absence . Structurally, the deaminase-like fold is present in four other superfamilies including the JAB-like metalloproteins, the C-terminal AICAR transformylase-catalyzing domains of PurH, Tm1506 and the formate dehydrogenase accessory subunit FdhD. The active site of the deaminases is composed of three residues that coordinate a zinc ion between conserved helices 2 and 3. The residues are typically found as [HCD]xE and CxxC motifs at the beginning of helices 2 and 3. The zinc ion activates a water molecule, which forms a tetrahderal intermediate with the carbon atom that is linked to the amine group. This is followed by deamination of the base.
The clan contains the following 33 members:A_deamin AICARFT_IMPCHas AID APOBEC1 APOBEC2 APOBEC3 APOBEC4 APOBEC4_like APOBEC_C APOBEC_N Bd3614-deam DAAD dCMP_cyt_deam_1 dCMP_cyt_deam_2 DddA-like DYW_deaminase FdhD-NarQ Inv-AAD LmjF365940-deam LpxI_C MafB19-deam NAD1 NAD2 OTT_1508_deam Pput2613-deam SNAD1 SNAD2 SNAD3 SNAD4 TM1506 Toxin-deaminase XOO_2897-deam YwqJ-deaminase
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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We make a range of alignments for each Pfam-A family:
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- alignment generated by searching the UniProtKB sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.
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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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.
|Number in seed:||19|
|Number in full:||213|
|Average length of the domain:||178.50 aa|
|Average identity of full alignment:||25 %|
|Average coverage of the sequence by the domain:||37.07 %|
|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:||14|
|Download:||download the raw HMM for this family|
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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
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:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
Anomalies in the taxonomy tree
There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
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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.
Too many species/sequences
For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
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.
If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.
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 APOBEC_N domain has been found. There are 28 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.
|Protein||Predicted structure||External Information|
|B3DGZ0||View 3D Structure||Click here|
|Q23460||View 3D Structure||Click here|
|Q8IUX4||View 3D Structure||Click here|
|Q8WW27||View 3D Structure||Click here|