Armadillo repeat explained

An armadillo repeat is a characteristic, repetitive amino acid sequence of about 42 residues in length that is found in many proteins. Proteins that contain armadillo repeats typically contain several tandemly repeated copies.[1] [2] Each armadillo repeat is composed of a pair of alpha helices that form a hairpin structure. Multiple copies of the repeat form what is known as an alpha solenoid structure.

Examples of proteins that contain armadillo repeats include β-catenin, Sarm1 (SARM1),[3] α-importin,[4] plakoglobin,[5] adenomatous polyposis coli (APC),[6] and many others.

The term armadillo derives from the historical name of the β-catenin gene in the fruitfly Drosophila where the armadillo repeat was first discovered. Although β-catenin was previously believed to be a protein involved in linking cadherin cell adhesion proteins to the cytoskeleton, recent work indicates that β-catenin regulates the homodimerization of alpha-catenin, which in turn controls actin branching and bundling.[7] 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.

Structure

The 3-dimensional fold of an armadillo repeat was first observed in the crystal structure of β-catenin, where the 12 tandem repeats form a superhelix of alpha helices with three helices per unit. The cylindrical structure features a positively charged groove, which presumably interacts with the acidic surfaces of the known interaction partners of β-catenin.[8]

External links

Notes and References

  1. Peifer M, Berg S, Reynolds AB . A repeating amino acid motif shared by proteins with diverse cellular roles . Cell . 76 . 5 . 789–91 . 1994 . 7907279 . 10.1016/0092-8674(94)90353-0 . 26528190 .
  2. Groves MR, Barford D . Topological characteristics of helical repeat proteins . Current Opinion in Structural Biology . 9 . 3 . 383–9 . 1999 . 10361086 . 10.1016/S0959-440X(99)80052-9 .
  3. Web site: Scopus preview - Scopus - Welcome to Scopus . 2023-03-21 . www.scopus.com.
  4. Herold A, Truant R, Wiegand H, Cullen BR . Determination of the functional domain organization of the importin alpha nuclear import factor . J. Cell Biol. . 143 . 2 . 309–18 . October 1998 . 9786944 . 2132842 . 10.1083/jcb.143.2.309 .
  5. McCrea PD, Turck CW, Gumbiner B . A homolog of the armadillo protein in Drosophila (plakoglobin) associated with E-cadherin . Science . 254 . 5036 . 1359–61 . November 1991 . 1962194 . 10.1126/science.1962194 . 1991Sci...254.1359M .
  6. Hirschl D, Bayer P, Müller O . Secondary structure of an armadillo single repeat from the APC protein . FEBS Lett. . 383 . 1–2 . 31–6 . March 1996 . 8612785 . 10.1016/0014-5793(96)00215-3 . 36190869 .
  7. Nusse, Roel, and Hans Clevers. “Wnt/β-Catenin Signaling, Disease, and Emerging Therapeutic Modalities.” Cell, vol. 169, no. 6, 1 June 2017, pp. 985–999., doi:10.1016/j.cell.2017.05.016.
  8. Web site: Armadillo (IPR000225) . InterPro . EMBL-EBI .