Apolipoprotein C3

Apolipoprotein C-III
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 2JQ3
Identifiers
Symbols	APOC3 ; APOCIII; HALP2
External IDs	OMIM: 107720 MGI: 88055 HomoloGene: 81615 GeneCards: APOC3 Gene
Gene ontology Molecular function • phospholipid binding • cholesterol binding • enzyme regulator activity • lipase inhibitor activity • high-density lipoprotein particle receptor binding Cellular component • extracellular region • extracellular space • early endosome • very-low-density lipoprotein particle • intermediate-density lipoprotein particle • spherical high-density lipoprotein particle • chylomicron • extracellular exosome Biological process • retinoid metabolic process • triglyceride metabolic process • G-protein coupled receptor signaling pathway • phototransduction, visible light • negative regulation of triglyceride catabolic process • negative regulation of very-low-density lipoprotein particle remodeling • negative regulation of very-low-density lipoprotein particle clearance • negative regulation of high-density lipoprotein particle clearance • negative regulation of low-density lipoprotein particle clearance • triglyceride catabolic process • regulation of Cdc42 protein signal transduction • cholesterol efflux • phospholipid efflux • high-density lipoprotein particle remodeling • very-low-density lipoprotein particle assembly • chylomicron remnant clearance • lipoprotein metabolic process • cholesterol homeostasis • reverse cholesterol transport • small molecule metabolic process • negative regulation of fatty acid biosynthetic process • negative regulation of lipid metabolic process • negative regulation of receptor-mediated endocytosis • negative regulation of lipid catabolic process • negative regulation of lipoprotein lipase activity • negative regulation of cholesterol import • triglyceride homeostasis Sources: Amigo / QuickGO
RNA expression pattern
File:PBB GE APOC3 205820 s at tn.png
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	345	11814
Ensembl	ENSG00000110245	ENSMUSG00000032081
UniProt	P02656	P33622
RefSeq (mRNA)	NM_000040	NM_023114
RefSeq (protein)	NP_000031	NP_075603
Location (UCSC)	Chr 11: 116.83 – 116.83 Mb	Chr 9: 46.23 – 46.24 Mb
PubMed search	[1]	[2]

Apolipoprotein C-III also known as apo-CIII is a protein that in humans is encoded by the APOC3 gene. Apo-CIII is a component of very low density lipoprotein (VLDL).

Structure

ApoC-III
Identifiers
Symbol	ApoC-III
Pfam	PF05778
InterPro	IPR008403
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

ApoCIII is a relatively small protein containing 79 amino acids that can be glycosylated at threonine-74. The most abundant glycoforms are characterized by an O-linked disaccharide galactose linked to N-acetylgalactosamine (Gal- GalNAc), further modified with up to 2 sialic acid residues. Less abundant glycoforms are characterized by more complex and fucosylated glycan moieties.

Function

APOC3 inhibits lipoprotein lipase and hepatic lipase; it is thought to inhibit hepatic uptake of triglyceride-rich particles. The APOA1, APOC3 and APOA4 genes are closely linked in both rat and human genomes. The A-I and A-IV genes are transcribed from the same strand, while the A-1 and C-III genes are convergently transcribed. An increase in apoC-III levels induces the development of hypertriglyceridemia. Recent evidences suggest an intracellular role for Apo-CIII in promoting the assembly and secretion of triglyceride-rich VLDL particles from hepatic cells under lipid-rich conditions. However, two naturally occurring point mutations in human apoC3 coding sequence, namely Ala23Thr and Lys58Glu have been shown to abolish the intracellular assembly and secretion of triglyceride-rich VLDL particles from hepatic cells.

Clinical significance

Two novel susceptibility haplotypes (specifically, P2-S2-X1 and P1-S2-X1) have been discovered in ApoAI-CIII-AIV gene cluster on chromosome 11q23; these confer approximately threefold higher risk of coronary heart disease in normal as well as non-insulin diabetes mellitus. Apo-CIII delays the catabolism of triglyceride rich particles. Elevations of Apo-CIII found in genetic variation studies may predispose patients to non-alcoholic fatty liver disease.

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.

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|px|alt=Statin Pathway edit]]

File:StatinPathway_WP430.png

Statin Pathway edit

See also

• Apolipoprotein C

Apolipoprotein CIII is also on HDL partilcles.

External links

• Apolipoprotein C-III at the US National Library of Medicine Medical Subject Headings (MeSH)