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. This is the function of Ensembl gene identifier ENSG00000110244 (APOA4, apolipoprotein A4).