Coiled coils: a highly versatile protein folding motif

The alpha -helical coiled coil is one of the principal subunit oligomerizat ion motifs in proteins. Its most characteristic feature is a heptad repeat pattern of primarily apolar residues that constitute the oligomer interface . Despite its simplicity, it is a highly versatile folding motif: coiled-co il-containing proteins exhibit a broad range of different functions related to the specific 'design' of their coiled-coil domains. The architecture of a particular coiled-coil domain determines its oligomerization state, rigi dity and ability to function as a molecular recognition system. Much progre ss has been made towards understanding the factors that determine coiled-co il formation and stability. Here we discuss this highly versatile protein f olding and oligomerization motif with regard to its structural architecture and how this is related to its biological functions.