PCSK9, a member of the peptidase S8 family, reveals four major components in the pre-processed protein: the signal peptide; the N-terminal prodomain (has a flexible crystal structure); the catalytic domain; and the C-terminal domain, which is further divided into three modules.
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is an enzyme encoded by the PCSK9 gene in humans on chromosome 1. PCSK9 is a member of the peptidase S8 family. The solved structure of PCSK9 reveals four major components in the pre-processed protein: the signal peptide (residues 1-30); the N-terminal prodomain (residues 31-152); the catalytic domain (residues 153-425); and the C-terminal domain (residues 426-692), which is further divided into three modules. 
