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. KCTD16 (potassium channel tetramerisation domain containing 16), also known as BTB/POZ domain-containing protein KCTD16, is a 428 amino acid protein that contains one BTB (POZ) domain. An auxiliary subunit of GABAB R1 and GABAB R2, KCTD16 increases agonist potency and alters the G-protein signaling of the receptors by accelerating onset and promoting desensitization.