Calponin homology domain (or CH domain) is a family of actin binding domains found in both cytoskeletal proteins and signal transduction proteins. The domain is about 100 amino acids in length and is composed of four alpha helices. It comprises the following groups of actin-binding domains: * Actinin-type (including spectrin, fimbrin, ABP-280) * Calponin-type A comprehensive review of proteins containing this type of actin-binding domains is given in.