PCSK9 is the 9th member of the proprotein convertase family of proteins that activate other proteins. PCSK9 is ubiquitously expressed in many tissues and cell types. PCSK9 binds to the receptor for low-density lipoprotein particles (LDL), which typically transport 3,000 to 6,000 fat molecules (including cholesterol) per particle, within extracellular fluid. PCSK9 has medical importance because it acts in lipoprotein homeostasis. Agents which block PCSK9 can lower LDL particle concentrations. PCSK9 may also have a role in the differentiation of cortical neurons.
