The paraoxonase 1, 2 and 3 in humans.

The paraoxonase gene family in humans includes three members: PON1, PON2 and PON3. The products of those three genes are the following enzymes: paraoxonase 1 (PON1), paraoxonase 2 (PON2) and paraoxonase 3 (PON3). PON1 is mainly associated with a high density lipoprotein (HDL). A small amount of this enzyme is also bound to very low-density lipoprotein (VLDL) and postprandial chylomicrons. PON1 possess organophosphatase, arylesterase and lactonase activity and it hydrolyzes many different substrates. It is also known that PON1 may have antiatherogenic function. Compared to the PON1, PON2 and PON3 are much less studied and described. PON2 is ubiquitously expressed intracellular protein, while PON3 is bound to HDL, like PON1. The both enzymes possess antioxidant properties.