KLHL18 is a 574 amino acid protein that is related to the Drosophila kelch protein, which is required to maintain actin organization in ovarian ring canals. Mutations affecting Kelch function result in failure of Kelch to associate with the ring canals and subsequent female sterility. Human KLHL18 protein contains six kelch repeats, one BACK (BTB/Kelch associated) domain 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. There are two isoforms of KLHL18 that are produced as a result of alternative splicing events.