Factor VII-activating protease (FSAP) is a serine-protease present in human plasma as a single-chain pro-enzyme (64 kDa) at a concentration of 12 µg/ml. The pro-enzyme can be activated by an autocatalytic mechanism or by urokinase generating the active two-chain form (40 and 30 kDa). The activity of FSAP is strongly dependent on Ca2+ ions and is efficiently inhibited by alpha2-antiplasmin and aprotinin.

FSAP has the ability to activate both coagulation factor VII (independent of tissue factor) and pro-urokinase. Thus, FSAP has a dual function as a potent pro-coagulant and pro-fibrinolytic agent.

Diagnostic relevance
Recently a frequent (5 – 10% of healthy subjects) variant of FSAP with a single nucleotide polymorphism (SNP) has been identified, termed “Marburg I” (FSAP-MI). The FSAP-MI variant shows diminished activity in pro-urokinase activation, whereas the capacity to activate Factor VII is normal. The FSAP-MI variant was found to be a significant risk predictor for the evolution and progression of carotid stenosis.

Pathophysiology
The FSAP-MI variant shows diminished activity in pro-urokinase activation, whereas the capacity to activate Factor VII is normal. It seems likely that FSAP-MI, due to the resulting hemostatic imbalance, may promote the development of thrombo-embolic diseases. Accordingly, the FSAP-MI variant was found to be a risk factor for the evolution and progression of atherogenesis.

Indication

• Thromboembolic diseases
• Risk predictor for progression of atherogenesis, in particular for carotid stenosis.

Aliases

• Plasma hyaluronan binding protein (PHBP)
• Hyaluronan-binding protein 2 (HABP2)

More information

• Molecular information on FSAP in NCBI’s OMIM database can be found here ^[1]
• Information on detection methods are summarized here ^[2].
• Info on commercial research reagents and assays can be found here ^[3].
• A complimentary compilation of abstracts of current scientific publications on FSAP can be down-loaded here ^[4].
• A complimentary compilation of test protocols for functional testing of FSAP
  in biological fluids can be down-loaded here ^[5].