The tumour suppressor protein, APC, has a nuclear export activity as well as many different intracellular functions. The structure consists of three alpha-helices forming two separate antiparallel coiled coils [1].

1: The coiled coil region (amino acids 129-250) of the tumor suppressor protein adenomatous polyposis coli (APC). Its structure and its interaction with chromosome maintenance region 1 (Crm-1). Tickenbrock L, Cramer J, Vetter IR, Muller O; J Biol Chem. 2002;277:32332-32338. PMID:12070164