The BTB domain of kelch proteins (if present) allows the formation of homo- or heterodimers that mediate protein–protein interactions.

Each kelch repeat forms a "blade" of the β-propeller fold, consisting of a four-stranded antiparallel β-sheet secondary structure, arranged radially around a central axis, packed onto its adjoining repeats via hydrophobic contacts.

Kelch-repeat β-propellers undergo a variety of binding interactions with other proteins, notably the actin filaments of a cell.

Kelch-like proteins are known to act as substrate adaptors for Cullin 3 ubiquitin ligases.

Kelch proteins have also been isolated in many other animals, plants, bacteria, fungi, and even virus (restricted to Poxviridae).