A<unk>  is a structural motif in proteins, in which 2-7 alpha-helices are<unk>  together like the strands of a rope (Dimers and trimers are the most common types). Many<unk>  type proteins are involved in important biological functions such as the regulation of gene expression e.g. transcription factors. Notable examples are the proteins the oncoproteins c-fos and jun, and the muscle protein tropomyosin.
Coiled coil
Continuous wave
Mosaic 
Complex 
Lentulo spiral
Piped link
Heave
Diradical