Thromb Haemost 1995; 73(04): 702-705
DOI: 10.1055/s-0038-1653844
Original Articles
Platelets
Schattauer GmbH Stuttgart

Transformation of Cellular Factor XIII into an Active Zymogen Transglutaminase in Thrombin-Stimulated Platelets

László Muszbek
The Department of Clinical Chemistry, University School of Medicine, Debrecen, Hungary
,
Gizella Haramura
The Department of Clinical Chemistry, University School of Medicine, Debrecen, Hungary
,
János Polgár
The Department of Clinical Chemistry, University School of Medicine, Debrecen, Hungary
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Publikationsverlauf

Received 13. Oktober 1994

Accepted after revision 09. Januar 1995

Publikationsdatum:
09. Juli 2018 (online)

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Summary

The cellular form of blood coagulation factor XIII (FXIII) is present in platelets, monocytes and macrophages. During long-term stimulation of platelets by thrombin cellular FXIII becomes activated and crosslinks proteins, however, the mechanism of its activation has not been elucidated. It was shown that, contrary to plasma FXIII, the intracellular activation of platelet FXIII does not involve proteolysis. FXIII remained intact in thrombin-activated platelets, i.e., the activation peptide was not removed from the molecule. Part of the zymogen FXIII molecules, however, assumed an active configuration as was demonstrated both by the measurement of transglutaminase activity and by active-site-SH titration. These findings clearly indicate that during platelet activation, when intracellular Ca2+ concentration is raised, a slow non-proteolytic transformation of FXIII zymogen into an active transglutaminase occurs.