DARPins and other repeat protein scaffolds: advances in engineering and applications

► Designed repeat protein scaffolds form a promising alternative to antibodies. ► These proteins lack disulfides, allowing soluble expression in the cytoplasm of E. coli. ► Novel molecular formats can be engineered in a convenient manner. ► DARPins, TPRs, αREPs and armadillos are examples of consensus designed scaffolds. ► Novel applications of these proteins, particularly DARPins, are highlighted.