pregnancy zone protein; C3 & PZP-like alpha-2-macroglobulin domain-containing protein 6 (PZP, CPAMD6)

Function

• able to inhibit all four classes of proteinases by a unique 'trapping' mechanism
• PZP has a peptide stretch, called the 'bait region' which contains specific cleavage sites for different proteinases (as does alpha-2 macroglobulin)
• when a proteinase cleaves the bait region, a conformational change is induced in PZP which traps the proteinase
• the entrapped enzyme remains active against low molecular weight substrates (activity against high molecular weight substrates is greatly reduced)
• following cleavage in the bait region, a thioester bond is hydrolyzed & mediates the covalent binding of the protein to the proteinase

Structure

• homotetramer, which consists of two pairs of disulfide-linked chains
• belongs to the protease inhibitor I39 (alpha-2-macroglobulin) family

Compartment

secreted

Alternative splicing

named isoforms=2

Expression

• plasma
• prominent constituent of late-pregnancy sera

More general terms

• secreted protein
• protease inhibitor
• glycoprotein

Database

• OMIM: https://mirror.omim.org/entry/176420
• UniProt: http://www.uniprot.org/uniprot/P20742.html