[7] It is a GLA domain protein and thus Vitamin K-dependent, and its functionality is therefore impaired in warfarin therapy.

Although it is not enzymatically active, it is structurally related to several serine proteases of the coagulation cascade: Factors VII, IX, X and Protein C. The carboxyglutamate residues (which require Vitamin K) bind Protein Z to phospholipid surfaces.

Others, however, link it to bleeding tendency; there is no clear explanation for this, as it acts physiologically as an inhibitor, and deficiency would logically have led to a predisposition for thrombosis.

Protein Z was first isolated in cattle blood by Christopher Prowse and Peter Esnouf in 1977,[9] and Broze & Miletich determined it in human plasma in 1984.

To test this, Vitamin K dependents were removed from the sample by adsorption to barium citrate, then an ion exchange chromatography was performed.

It has been found that if it isn't functioning correctly, it can lead to fetal death or hypersensitive disorders in pregnancy.

This happens because when the levels of this protein drop too low, it can lead to fetal growth restrictions.