APOA4 [SEP] chromosome
APOA4
Apolipoprotein A-IV (also known as apoA-IV, apoAIV, or apoA4) is plasma protein that is the product of the human gene APOA4.
Gene.
APOA4 resides on chromosome 11 in close linkage to APOA1 and APOC3. APOA4 contains 3 exons separated by two introns, and is polymorphic, although most of the reported sequence polymorphisms occur in exon 3. The best validated and studied non-synonymous SNPs are a glutamine → histidine substitution at codon 360 and a threonine → serine substitution at codon
347; a sequence polymorphism has also been identified in the 3'UTR of the third exon. Intra-species comparative gene sequence analysis suggests that the APOA4 gene arose from APOA1 by gene duplication approximately 270 MYA.
Function.
The primary translation product of the APOA4 gene is a 396-residue preprotein, which undergoes proteolytic processing to yield apo A-IV, a 376-residue mature O-linked glycoprotein. In most mammals, including humans, apo A-IV synthesis is confined to the intestine; however in mice and rats hepatic synthesis