An armadillo repeat is the name of a characteristic, repetitive
amino acid sequence of about 40
residues
Residue may refer to:
Chemistry and biology
* An amino acid, within a peptide chain
* Crop residue, materials left after agricultural processes
* Pesticide residue, refers to the pesticides that may remain on or in food after they are appli ...
in length that is found in many proteins. Proteins that contain armadillo repeats typically contain several
tandemly repeated copies.
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,
α-importin,
,
(APC),
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
Cadherins (named for "calcium-dependent adhesion") are a type of cell adhesion molecule (CAM) that is important in the formation of adherens junctions to allow cells to adhere to each other . Cadherins are a class of type-1 transmembrane proteins, ...
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.
[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.
] 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
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...
.
Structure
The 3-dimensional fold of an armadillo repeat was first observed in the crystal structure of beta-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 beta-catenin.
References
External links
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Armadillo/plakoglobin ARM repeatin
PROSITE
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