Proprotein convertase subtilisin/kexin type 9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein that in humans is encoded by the PCSK9 gene. PCSK9 is an enzyme which plays a key role in the regulation of low-density lipoprotein (LDL) receptor levels and function, and hence in the control of cholesterol homeostasis.

Pronunciation

The pronunciation of Proprotein convertase subtilisin/kexin type 9 is: pro-protein con-vert-ase sub-til-ih-sin/kex-in type nine.

Etymology

The term "Proprotein convertase subtilisin/kexin type 9" is derived from its function and structure. "Proprotein convertase" refers to the enzyme's role in converting proproteins into their active forms. "Subtilisin/kexin" refers to the type of protease domain that the enzyme contains, which is similar to those found in the subtilisin and kexin families of proteases. The "type 9" indicates that it is the ninth member of the proprotein convertase family.

Function

PCSK9 binds to the low-density lipoprotein receptor (LDLR), leading to LDLR degradation in lysosomes. The normal function of LDLR is to remove low-density lipoprotein (LDL), the so-called "bad cholesterol", from the bloodstream. Therefore, when PCSK9 prevents LDLR from removing LDL from the bloodstream, LDL-cholesterol levels increase.

Related Terms

• Proprotein convertase: A type of enzyme that activates other proteins by cutting them at specific sites.
• Subtilisin: A family of proteases, or proteins that cut other proteins.
• Kexin: A type of protease found in yeast.
• Low-density lipoprotein receptor (LDLR): A molecule that binds low-density lipoprotein and removes it from the bloodstream.
• Lysosome: A part of the cell that breaks down waste materials and cellular debris.

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