The many faces of epidermal growth factor repeats.

Epidermal growth factor (EGF) is a short peptide with a distinctive motif of six cysteines. This motif is found in many different proteins of diverse functions. One approach to determining the functional utility of EGF repeats is to undertake a methodical analysis of each individual protein. While this approach has met with some success, it has been applied to only a small fraction of all the EGF repeat-bearing proteins. A second approach is to consider all these proteins as a whole but give particular attention to structural and functional similarities. This review attempts a broad, although not comprehensive, survey of the families of proteins containing EGF repeats, with particular emphasis on the relative distribution of calcium-binding and noncalcium-binding EGF repeats.