PCSK9 (前蛋白转化酶/枯草溶菌素9)

The protein convertase subtilisin/kexin type 9 (PCSK9) is an enzyme encoded by the PCSK9 gene located on human chromosome 1. It is the ninth member of the protein convertase family, a group of enzymes that can activate homologous genes found in many species^[1]. PCSK9 is a liver-synthesized protease that plays a major role in regulating the levels of low-density lipoprotein receptors (LDLR) on the surface of liver cells and can inhibit the LDLR recycling pathway. PCSK9 binds to LDLR on the surface of liver cells, escorts LDLR to lysosomes for degradation, and prevents LDLR from recirculating to the cell membrane, effectively increasing the level of circulating LDL. Therefore, inhibiting the activity of the PCSK9 protease can down-regulate circulating LDL levels. PCSK9 is closely associated with various cardiovascular diseases, especially hypercholesterolemia and atherosclerosis^[2].