APOB: Apolipoprotein B is a major protein constituent of chylomicrons (apo B-48), LDL (apo B-100) and VLDL (apo B-100). Apo B-100 functions as a recognition signal for the cellular binding and internalization of LDL particles by the apoB/E receptor. Defects in APOB are a cause of familial hypobetalipoproteinemia type 1 (FHBL1). A disorder characterized by highly reduced plasma concentrations of low density lipoproteins, and dietary fat malabsorption. Clinical presentation may vary from no symptoms to severe gastrointestinal and neurological dysfunction similar to abetalipoproteinemia. Defects in APOB are a cause of familial ligand-defective apolipoprotein B-100 (FDB). FDB is a dominantly inherited disorder of lipoprotein metabolism leading to hypercholesterolemia and increased proneness to coronary artery disease (CAD). The plasma cholesterol levels are dramatically elevated due to impaired clearance of LDL particles by defective APOB/E receptors. Defects in APOB associated with defects in other genes (polygenic) can contribute to hypocholesterolemia.
Protein type: Secreted; Carrier; Secreted, signal peptide
Chromosomal Location of Human Ortholog: 2p24-p23
Cellular Component: Golgi apparatus; extracellular space; endoplasmic reticulum membrane; intracellular membrane-bound organelle; endoplasmic reticulum lumen; early endosome; extracellular region; cytosol; actin cytoskeleton; chylomicron; cell soma; cytoplasm; plasma membrane; endosome membrane
Molecular Function: heparin binding; protein binding; low-density lipoprotein receptor binding; cholesterol transporter activity; phospholipid binding
Biological Process: phototransduction, visible light; lipoprotein catabolic process; response to lipopolysaccharide; response to carbohydrate stimulus; post-embryonic development; response to selenium ion; triacylglycerol catabolic process; retinoid metabolic process; transmembrane transport; cholesterol metabolic process; receptor-mediated endocytosis; nervous system development; cholesterol transport; in utero embryonic development; regulation of cholesterol biosynthetic process; response to virus; lipoprotein metabolic process; cholesterol efflux; sperm motility; cholesterol homeostasis; fertilization; lipoprotein biosynthetic process; lipoprotein transport; artery morphogenesis; spermatogenesis; triacylglycerol mobilization; blood coagulation; leukocyte migration
Disease: Hypercholesterolemia, Autosomal Dominant, Type B; Hypobetalipoproteinemia, Familial, 1
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