Apolipoprotein A-II

Apolipoprotein A-II (APOA2) is a 100-amino acid protein that plays a structural role in high-density lipoprotein (HDL) metabolism by stabilizing HDL particles through lipid association (UniProt: P02652). The protein is involved in lipid transport and metabolism pathways, with no documented Mendelian disease associations in UniProt.

APOA2 is relevant to Alzheimer's Disease pathology. Proteomics analysis of post-mortem AD brain tissue versus age-matched controls revealed significant downregulation of APOA2, with a mean log2 fold-change of −1.1 across subcellular fractions (Chaparral AD proteomics). This downregulation suggests impaired HDL-mediated lipid metabolism in AD brain, which may contribute to the neuroinflammatory and metabolic dysfunction characteristic of the disease. The consistent reduction across multiple subcellular compartments indicates a global decrease in APOA2 protein levels in AD pathology.