Structural domains comprising this superfamily share the structure of the C-terminal CKK domain of the calmodulin-regulated associated (or CAMSAP) family of proteins. CAMSAP proteins present an N-terminal region that includes a CH domain, a central region with a predicted coiled-coil, and this C-terminal CKK domain which is involved in binding CAMSAP proteins to microtubules PMID:19508979.

The structure of the CKK domain is a beta-barrel with an associated alpha-helical hairpin. Characteristically, the CKK domain has a single invariant tryptophan residue within the core of the predicted beta-barrel. Residues that interact with this Trp to form part of this core are highly conserved too.