APOB

This gene product is the main apolipoprotein of chylomicrons and low density lipoproteins. It occurs in plasma as two main isoforms, apoB-48 and apoB-100: the former is synthesized exclusively in the gut and the latter in the liver. The intestinal and the hepatic forms of apoB are encoded by a single gene from a single, very long mRNA. The two isoforms share a common N-terminal sequence. The shorter apoB-48 protein is produced after RNA editing of the apoB-100 transcript at residue 2180 (CAA->UAA), resulting in the creation of a stop codon, and early translation termination. Mutations in this gene or its regulatory region cause hypobetalipoproteinemia, normotriglyceridemic hypobetalipoproteinemia, and hypercholesterolemia due to ligand-defective apoB, diseases affecting plasma cholesterol and apoB levels. [provided by RefSeq, Jul 2008]

Full Name

Apolipoprotein B

Function

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.

Biological Process

Artery morphogenesis Source: Ensembl
Cellular protein metabolic process Source: Reactome
Cellular response to prostaglandin stimulus Source: Ensembl
Cellular response to tumor necrosis factor Source: Ensembl
Cholesterol efflux Source: Ensembl
Cholesterol homeostasis Source: BHF-UCL
Cholesterol metabolic process Source: BHF-UCL
Cholesterol transport Source: BHF-UCL
Chylomicron assembly Source: Reactome
Chylomicron remnant clearance Source: Reactome
Chylomicron remodeling Source: Reactome
Fertilization Source: Ensembl
Flagellated sperm motility Source: Ensembl
In utero embryonic development Source: Ensembl
Leukocyte migration Source: Reactome
Lipoprotein biosynthetic process Source: Ensembl
Lipoprotein catabolic process Source: Ensembl
Lipoprotein transport Source: GO_Central
Low-density lipoprotein particle clearance Source: BHF-UCL
Low-density lipoprotein particle remodeling Source: BHF-UCL
Membrane organization Source: Reactome
Nervous system development Source: Ensembl
Positive regulation of cholesterol storage Source: BHF-UCL
Positive regulation of gene expression Source: Ensembl
Positive regulation of lipid storage Source: BHF-UCL
Positive regulation of macrophage derived foam cell differentiation Source: BHF-UCL
Post-embryonic development Source: Ensembl
Post-translational protein modification Source: Reactome
Receptor-mediated endocytosis Source: Reactome
Regulation of cholesterol biosynthetic process Source: Ensembl
Response to carbohydrate Source: Ensembl
Response to estradiol Source: Ensembl
Response to lipopolysaccharide Source: Ensembl
Response to selenium ion Source: Ensembl
Response to virus Source: UniProtKB
Retinoid metabolic process Source: Reactome
Spermatogenesis Source: Ensembl
Toll-like receptor signaling pathway Source: Reactome
Triglyceride catabolic process Source: Ensembl
Triglyceride mobilization Source: GO_Central
Very-low-density lipoprotein particle assembly Source: Reactome
Very-low-density lipoprotein particle clearance Source: Reactome

Cellular Location

Cytoplasm; Secreted; Lipid droplet

Involvement in disease

Hypobetalipoproteinemia, familial, 1 (FHBL1): The disease is caused by variants affecting the gene represented in this entry. Most cases of FHBL1 result from nonsense mutations in the APOB gene that lead to a premature stop codon, which generate prematurely truncated apo B protein products (PubMed:21981844). A disorder of lipid metabolism characterized by less than 5th percentile age- and sex-specific levels of low density lipoproteins, and dietary fat malabsorption. Clinical presentation may vary from no symptoms to severe gastrointestinal and neurological dysfunction similar to abetalipoproteinemia.
Hypercholesterolemia, familial, 2 (FHCL2): A form of hypercholesterolemia, a disorder of lipoprotein metabolism characterized by elevated serum low-density lipoprotein (LDL) cholesterol levels, which result in excess deposition of cholesterol in tissues and leads to xanthelasma, xanthomas, accelerated atherosclerosis and increased risk of premature coronary heart disease. FHCL2 inheritance is autosomal dominant.

PTM

Palmitoylated; structural requirement for proper assembly of the hydrophobic core of the lipoprotein particle.