Coiled coil

A coiled coil is a structural motif in proteins in which 2–7^[1] alpha-helices are coiled together like the strands of a rope. (Dimers and trimers are the most common types.) They have been found in roughly 5-10% of proteins and have a variety of functions.^[2] They are one of the most widespread motifs found in protein-protein interactions. To aid protein study, several tools have been developed to predict coiled-coils in protein structures.^[3] Many coiled coil-type proteins are involved in important biological functions, such as the regulation of gene expression — e.g., transcription factors. Notable examples are the oncoproteins c-Fos and c-Jun, as well as the muscle protein tropomyosin.