Kelch proteins (and Kelch-like proteins) are proteins that have repeated kelch domains. Most Kelch proteins also have a BTB (defn) domain. Each kelch domain forms the blade of a propellar structure, with the repeated kelch domains forming a Beta-propellar. The structure of this Beta-propellar is known but the function is not characterised. KLHDC4 contains six Kelch repeats. There are three named isoforms.