Members of this family are predominantly found in the actin-bundling protein Cortexillin I from Dictyostelium discoideum. They adopt a structure consisting of an 18-heptad-repeat alpha-helical coiled-coil, and are a prerequisite for the assembly of Cortexillin I [1].

1: The coiled-coil trigger site of the rod domain of cortexillin I unveils a distinct network of interhelical and intrahelical salt bridges. Burkhard P, Kammerer RA, Steinmetz MO, Bourenkov GP, Aebi U; Structure. 2000;8:223-230. PMID:10745004