A family of apolipoproteins (CI–CIV). Apo-CI (83 aa) constitutes ~10% of the protein of the VLDL (very low-density lipoprotein) and 2% of that of HDL (high-density lipoprotein) and appears to modulate the interaction of ApoE with VLDL. ApoC-II (101 aa) is a component of VLDL and is a necessary cofactor for the activation of lipoprotein lipase (EC 18.104.22.168). Mutations in the gene encoding ApoC2 cause hyperlipoproteinaemia type IB, an autosomal recessive disorder characterized by hypertriglyceridaemia, xanthomas, and susceptibility to pancreatitis and early atherosclerosis. ApoC-III (99 aa) forms 50% of the protein fraction of VLDL and inhibits lipoprotein lipase. Mutations cause deficiency of the apolipoprotein but without clinical consequences except perhaps a reduced risk of atherosclerosis. ApoC-IV (127 aa) is thought to be involved in lipoprotein metabolism.
Subjects: Medicine and Health.