Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9)

PCSK9 belonging to the proteinase K subfamily of the secretory subtilase family. The encoded protein is synthesized as a soluble zymogen that undergoes autocatalytic intramolecular processing in the endoplasmic reticulum. The protein may function as a proprotein convertase. This protein plays a major regulatory role in cholesterol homeostasis. PCSK9 binds to the epidermal growth factor-like repeat A (EGF-A) domain of the low-density lipoprotein receptor (LDLR), inducing LDLR degradation. Reduced LDLR levels result in decreased metabolism of low-density lipoproteins, which could lead to hypercholesterolemia. Inhibition of PSCK9 function is currently being explored as a means of lowering cholesterol levels. PCSK9 may also have a role in the differentiation of cortical neurons.