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497  structures 451  species 6  interactions 12724  sequences 321  architectures

Family: Arm (PF00514)

Summary: Armadillo/beta-catenin-like repeat

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This is the Wikipedia entry entitled "Armadillo repeats". More...

Armadillo repeats Edit Wikipedia article

Armadillo repeat domain
PDB 3bct EBI.jpg
Structure of the armadillo domain of beta-catenin.[1]
Symbol Arm
Pfam PF00514
Pfam clan CL0020
InterPro IPR000225
SCOP 3bct

Armadillo repeat is the name of a characteristic, repetitive amino acid sequence found in β-catenin and many other proteins, like α-importin,[2] plakoglobin,[3] or adenomatous polyposis coli (APC).[4] Its name derives from the historical name of the β-catenin gene in the fruitfly Drosophila: where they were first discovered. Armadillo repeats are approximately 40 amino acids long and proteins that contain them usually have many tandemly repeated copies.[5][6] These tandem repeats usually fold together to form a single, rigid protein domain called the armadillo (ARM) domain. Because ARM domains can consist of a variable number of repeats, they are a good example of solenoid protein domains. The best characterized example of armadillo domains is found in β-catenin. β-catenin is a protein involved in linking cadherin cell adhesion proteins to the cytoskeleton,[1] but the Armadillo repeat is found in a wide range of proteins with other functions. This type of protein domain is important in transducing WNT signals during embryonic development.


  1. ^ a b Huber AH, Nelson WJ, Weis WI (September 1997). "Three-dimensional structure of the armadillo repeat region of beta-catenin". Cell 90 (5): 871–82. doi:10.1016/S0092-8674(00)80352-9. PMID 9298899. 
  2. ^ Herold A, Truant R, Wiegand H, Cullen BR (October 1998). "Determination of the functional domain organization of the importin alpha nuclear import factor". J. Cell Biol. 143 (2): 309–18. doi:10.1083/jcb.143.2.309. PMC 2132842. PMID 9786944. 
  3. ^ McCrea PD, Turck CW, Gumbiner B (November 1991). "A homolog of the armadillo protein in Drosophila (plakoglobin) associated with E-cadherin". Science 254 (5036): 1359–61. doi:10.1126/science.1962194. PMID 1962194. 
  4. ^ Hirschl D, Bayer P, Müller O (March 1996). "Secondary structure of an armadillo single repeat from the APC protein". FEBS Lett. 383 (1-2): 31–6. doi:10.1016/0014-5793(96)00215-3. PMID 8612785. 
  5. ^ Peifer, M; Berg, S; Reynolds, AB (1994). "A repeating amino acid motif shared by proteins with diverse cellular roles". Cell 76 (5): 789–91. doi:10.1016/0092-8674(94)90353-0. PMID 7907279.  edit
  6. ^ Groves, MR; Barford, D (1999). "Topological characteristics of helical repeat proteins". Current opinion in structural biology 9 (3): 383–9. doi:10.1016/S0959-440X(99)80052-9. PMID 10361086.  edit

External links

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Armadillo/beta-catenin-like repeat Provide feedback

Approx. 40 amino acid repeat. Tandem repeats form super-helix of helices that is proposed to mediate interaction of beta-catenin with its ligands. CAUTION: This family does not contain all known armadillo repeats.

Literature references

  1. Huber AH, Nelson WJ, Weis WI; , Cell 1997;90:871-882.: Three-dimensional structure of the armadillo repeat region of beta-catenin. PUBMED:9298899 EPMC:9298899

  2. Gumbiner BM; , Curr Opin Cell Biol 1995;7:634-640.: Signal transduction of beta-catenin. PUBMED:8573337 EPMC:8573337

  3. Cavallo R, Rubenstein D, Peifer M; , Curr Opin Genet Dev 1997;7:459-466.: Armadillo and dTCF: a marriage made in the nucleus. PUBMED:9309175 EPMC:9309175

  4. Su LK, Vogelstein B, Kinzler KW; , Science 1993;262:1734-1737.: Association of the APC tumor suppressor protein with catenins. PUBMED:8259519 EPMC:8259519

  5. Rubinfeld B, Souza B, Albert I, Muller O, Chamberlain SH, Masiarz FR, Munemitsu S, Polakis P; , Science 1993;262:1731-1734.: Association of the APC gene product with beta-catenin. PUBMED:8259518 EPMC:8259518

  6. Peifer M, Wieschaus E; , Cell 1990;63:1167-1176.: The segment polarity gene armadillo encodes a functionally modular protein that is the Drosophila homolog of human plakoglobin. PUBMED:2261639 EPMC:2261639

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR000225

The armadillo (Arm) repeat is an approximately 40 amino acid long tandemly repeated sequence motif first identified in the Drosophila melanogaster segment polarity gene armadillo involved in signal transduction through wingless. Animal Arm-repeat proteins function in various processes, including intracellular signalling and cytoskeletal regulation, and include such proteins as beta-catenin, the junctional plaque protein plakoglobin, the adenomatous polyposis coli (APC) tumour suppressor protein, and the nuclear transport factor importin-alpha, amongst others [PUBMED:9770300]. A subset of these proteins is conserved across eukaryotic kingdoms. In higher plants, some Arm-repeat proteins function in intracellular signalling like their mammalian counterparts, while others have novel functions [PUBMED:12946625].

The 3-dimensional fold of an armadillo repeat is known from the crystal structure of beta-catenin, where the 12 repeats form a superhelix of alpha helices with three helices per unit [PUBMED:9298899]. The cylindrical structure features a positively charged grove, which presumably interacts with the acidic surfaces of the known interaction partners of beta-catenin.

Gene Ontology

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Domain organisation

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

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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 using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics 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.

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 HMMER3.

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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

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 View help on the curation process

Seed source: SMART
Previous IDs: Armadillo_seg;
Type: Repeat
Author: Bateman A, Ponting C, Schultz J, Bork P
Number in seed: 242
Number in full: 12724
Average length of the domain: 40.80 aa
Average identity of full alignment: 24 %
Average coverage of the sequence by the domain: 18.23 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 20.6 20.3
Trusted cut-off 20.6 20.3
Noise cut-off 20.5 20.2
Model length: 41
Family (HMM) version: 18
Download: download the raw HMM for this family

Species distribution

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There are 6 interactions for this family. More...

Arm APC_crr HEAT Axin_b-cat_bind Cadherin_C ICAT


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 Arm domain has been found. There are 497 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 seqence.

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