APOA1

ApoA-I is located on chromosome 11, specifically at 11q23-q24 . The gene contains four exons and encodes a protein composed of 243 amino acids, with a molecular weight of approximately 28.1 kDa . Due to alternative splicing, multiple transcript variants of APOA1 exist, including at least one that encodes a preprotein .

ApoA-I is essential for the formation and function of HDL particles . It facilitates the efflux of fat molecules from cells, including macrophages within arterial walls, by accepting fats from oxidized low-density lipoprotein (LDL) particles . This process is vital for transporting fats to the liver for excretion or back to LDL particles . ApoA-I also acts as a cofactor for lecithin-cholesterol acyltransferase (LCAT), an enzyme responsible for the formation of most plasma cholesteryl esters .

Additionally, ApoA-I has been identified as a prostacyclin (PGI2) stabilizing factor, which may contribute to its anticlotting effects . It is also used as a biomarker for predicting cardiovascular diseases, with the ratio of apoB-100/apoA-I (LDL vs. HDL particles) being a strong indicator of myocardial infarction event rates .

Defects in the APOA1 gene are associated with HDL deficiencies, including Tangier disease and systemic non-neuropathic amyloidosis . These conditions can lead to significant health issues due to impaired cholesterol transport and metabolism.

ApoA-I is routinely measured using immunoassays such as ELISA or nephelometry . It is also used to create in vitro lipoprotein nanodiscs for cell-free membrane expression systems .

Research on ApoA-I continues to uncover its diverse functions and potential therapeutic applications. Its role in cholesterol transport and cardiovascular health makes it a critical target for developing treatments for heart disease and related conditions .