Apolipoproteins are protein components of plasma lipoproteins. The apolipoprotein L gene family encodes six highly homologous proteins designated apoL 1-6, which are associated with large high density type lipoproteins (HDL). The human apoL family maps to chromosome 22q12.3 within a 127,000-bp region. ApoL2 and apoL3 may allow the binding of lipids to organ-elles or may be involved in the movement of lipids in the cytoplasm. ApoL2 localizes to the cytoplasm and is widely expressed, with the highest levels observed in the lung, thymus, pancreas, placenta, adult brain and prostate. The apoL2 protein is also detected in the spleen, liver, kidney, colon, small intestine, uterus, spinal cord, adrenal gland, salivary gland, trachea, mammary gland, skeletal muscle, testis and fetal brain and liver. ApoL3 also localizes to the cytoplasm and is widely expressed, with highest levels detected in the prostate, lung and placenta. It is also detected in kidney, bone marrow, spleen, thymus, spinal cord, adrenal gland, salivary gland, trachea and mammary gland. Lower levels of apoL3 are observed in the brain, heart, fetal liver, pancreas and testis.