Strength Through Repetition

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Science  19 May 2000:
Vol. 288, Issue 5469, pp. 1137
DOI: 10.1126/science.288.5469.1137d

Many invertebrates secrete a protective external cuticle that is composed of extracellular matrix and that forms strong adhesive connections with the underlying epithelia. Wilkin et al. have characterized an unusual component of the cuticle-epithelial cell junction in the fruit fly Drosophila, a protein called Dumpy. Gigantic in size (2.5 megadalton), Dumpy represents an extreme form of modular protein construction, containing 308 epidermal growth factor (EGF) modules interspersed with 185 copies of a new module (DPY), along with a cross-linking domain and a membrane-anchoring domain. The structural properties of the EGF-DPY-EGF triad predict that Dumpy forms a fiber that is nearly one micrometer in length. Insertion and cross-linking of the fiber within the cuticle may provide a strong anchor for underlying tissue, allowing it to support mechanical tension at sites under stress.—PAK

Curr. Biol.10, 559 (2000).

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