KLHL2 is a 593 amino acid actin-binding protein. Highly expressed in brain, KLHL2 is thought to play a role in the organization of the actin cytoskeleton in brain cells. KLHL3 (kelch-like protein 3), is a 587 amino acid protein active in the protein ubiquitination pathway. KLHL3 is thought to be a substrate-specific adapter of an E3 ubiquitin-ligase complex that mediates the ubiquitination of target proteins, which leads to proteasomal degradation of the target protein. KLHL2 and KLHL3 proteins contain six kelch repeats and one BTB (POZ) domain. The BTB (Broad-Complex, Tramtrack and Bric a brac) domain, also known as the POZ (Poxvirus and Zinc finger) domain, is an N-terminal homodimerization domain that contains multiple copies of kelch repeats and/or C2H2-type zinc fingers. Proteins that contain BTB domains are thought to be involved in transcriptional regulation via control of chromatin structure and function.