Coiled coil

A coiled coil is a structural motif found in many proteins. It consists of 2–5 alpha-helices that are coiled together like the strands of a rope. Dimers and trimers are the most common ones. Coiled coils usually containt a repeated seven residue pattern called heptad repeats.

Coiled coils are held together by hydrophobic forces. When two or more alpha-helices have repeating patterns of hydrophobic amino acid side chains, the most favorable way for them to conform in the water-filled environment of the cytoplasm is to wrap the hydrophobic strands against each other sandwiched between the hydrophylic amino acids.