KLHL15 is believed to be a substrate-specific adapter of an E3 ubiquitin-protein ligase complex which regulates the ubiquitination, and subsequent proteasomal degradation, of target proteins. KLHL15 contains one BACK (BTB/Kelch associated) domain, five kelch repeats and one BTB 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.