Apolipoprotein A1 is a protein that in humans is encoded by the APOA1 gene. It has a specific role in lipid metabolism. The text in a recent report suggested that APOA1 mRNA is regulated by endogenously expressed antisense RNA.

The APOA1 gene is located on the 11th chromosome, with its specific location being 11q23-q24. The gene contains 4 exons. APOA1 encodes a 45.4 kDa protein that is composed of 396 amino acids; 21 peptides have been observed through mass spectrometry data. Apolipoprotein A1 is the major protein component of high density lipoprotein (HDL) in plasma. Chylomicrons secreted from the intestinal enterocyte also contain apo A1, but it is quickly transferred to HDL in the bloodstream.