Semin Thromb Hemost 2007; 33(1): 046-052
DOI: 10.1055/s-2006-958461
Copyright © 2007 by Thieme Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.

The Interaction among Protein C Inhibitor, Prostate-Specific Antigen, and the Semenogelin System

Koji Suzuki1 , Hideaki Kise2 , Junji Nishioka1 , Tatsuya Hayashi1
  • 1Department of Molecular Pathobiology, Mie University Graduate School of Medicine, Tsu-city, Mie, Japan
  • 2Department of Urology, Mie University Graduate School of Medicine, Tsu-city, Mie, Japan
Further Information

Publication History

Publication Date:
29 January 2007 (online)


The kallikrein-like serine protease, prostate-specific antigen (PSA), is mixed in human seminal plasma with its protein substrates semenogelin (Sg) -I, Sg-II, and protein C inhibitor (PCI), which are produced in seminal vesicles. In the seminal plasma, PSA degrades Sg-I, and Sg-II, which are major components in insoluble coagula, and PCI inhibits PSA by forming a PSA-PCI complex. Digestion of seminal coagula with PSA releases PCI and PSA-PCI complex from the coagula into a soluble phase, suggesting the presence of active PCI within the coagula. PCI forms a ternary complex with PSA and Sg-II in the seminal plasma. The binding of Sg-II to PSA and PCI is influenced by pH, ionic strength, heparin, negatively charged dextran sulfate, divalent cations, and particularly by Zn2 +. These observations suggest that binding of PCI to Sg in seminal vesicles regulates the PSA-catalyzed degradation of Sg in seminal plasma; the complex formation among PCI, PSA, and Sg is modulated by several factors in seminal plasma.


Professor Koji Suzuki, Ph.D. 

Mie University Graduate School of Medicine

Edobashi 2-174, Tsu-city, Mie, 514-8507, Japan

Email: [email protected]