ARM

Armadillo/beta-catenin-like repeats
ARM
SMART accession number:SM00185
Description: Approx. 40 amino acid repeat. Tandem repeats form superhelix of helices that is proposed to mediate interaction of beta-catenin with its ligands. Involved in transducing the Wingless/Wnt signal. In plakoglobin arm repeats bind alpha-catenin and N-cadherin.
Interpro abstract (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.

GO function:protein binding (GO:0005515)
Family alignment:
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There are 47424 ARM domains in 8057 proteins in SMART's nrdb database.

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