Apoliprotein (apo) A-IV gene contains 3 exons separated by two introns. A sequence polymorphism has been identified in the 3'UTR of the third exon. The primary translation product is a 396-residue preprotein which after proteolytic processing is secreted its primary site of synthesis, the intestine, in association with chylomicron particles. Although its precise function is not known, apo A-IV is a potent activator of lecithin-cholesterol acyltransferase in vitro. [provided by RefSeq, Jul 2008],
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Function:
Domain:Nine of the thirteen 22-amino acid tandem repeats (each 22-mer is actually a tandem array of two, A and B, related 11-mers) occurring in this sequence are predicted to be highly alpha-helical, and many of these helices are amphipathic. They may therefore serve as lipid-binding domains with lecithin:cholesterol acyltransferase (LCAT) activating abilities.,Function:May have a role in chylomicrons and VLDL secretion and catabolism. Required for efficient activation of lipoprotein lipase by ApoC-II; potent activator of LCAT. Apoa-IV is a major component of HDL and chylomicrons.,online information:The Singapore human mutation and polymorphism database,polymorphism:Eight alleles have been characterized (APOA-IV*0 to APOA-IV*7). APOA-IV*1 is the major allele (90%), APOA-IV*2 is also common (8%), the others are rare alleles.,similarity:Belongs to the apolipoprotein A1/A4/E family.,tissue specificity:Synthesized primarily in the intestine and secreted in plasma.,
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Cellular Localization:
Secreted.
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Tissue Expression:
Synthesized primarily in the intestine and secreted in plasma.
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Research Areas:
>>Fat digestion and absorption ;
>>Vitamin digestion and absorption ;
>>Cholesterol metabolism ;
>>Lipid and atherosclerosis