Natural and artificial peptide motifs: their origins and the application of motif-programming.

In this tutorial review, I discuss the nature and application of peptide motifs. Motifs are usually identified through analysis of the sequence of natural proteins and are linked to particular biological functions, though the association between a motif and its function is only speculative in some cases. In other cases, however, the transplantability and functional independence of motifs have been experimentally proven, providing us with the opportunity to use those motifs as programming units for biotechnological application. In addition to natural motifs, peptide aptamers created using in vitro evolution systems can also serve as motif units. The associated functions of these artificial motifs are related to their binding ability. Numerous binders against both natural biomolecules and inorganic materials have been created from peptide phage systems. By programming these natural and artificial motifs, artificial proteins with the potential to contribute to medical diagnosis and treatment, nanotechnology, and various areas of basic science have been created. In addition, the transplantability and functional independence of motifs provide insight into the nature of protein evolution.