C20orf3, also known as APMAP (adipocyte plasma membrane-associated protein), is a 416 amino acid single-pass type II membrane protein that belongs to the strictosidine synthase family and is thought to play a role in adipocyte differentiation. The gene encoding C20orf3 maps to human chromosome 20, which houses over 600 genes some of which are associated with Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis, spinal muscular atrophy, ring chromosome 20 epilepsy syndrome and Alagille syndrome. Additionally, chromosome 20 contains a region with numerous genes which are thought important for seminal production and may be potential targets for male contraception