A few immobilized thrombins are sufficient for platelet spreading

Yosuke Okamura, Roman Schmidt, Ines Raschke, Maik Hintze, Shinji Takeoka, Alexander Egner, Thorsten Lang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Eukaryotic cells respond to signaling molecules with picomolar to nanomolar sensitivities. However, molar concentrations give no suggestion of the sufficient number of molecules per cell and are confusing when referring to physiological situations in which signaling molecules act in an immobilized state. Here, we studied platelet adhesion by thrombin, a key step in normal hemostasis and pathological arterial thrombosis. We generated a biofunctional nanosheet surface to mimic the in vivo solid-state interaction between platelets and thrombin at sites of injured tissues. We observed that <10 molecules readily activate platelets with high specificity, resulting in platelet adhesion and spreading. This number is much lower than expected from previous experiments in solution, in which the sole activation of platelets required a >1000-fold stoichiometric excess of thrombin. We conclude that immobilizing thrombin apposed to the membrane receptor allows platelets to respond with very high sensitivity. Moreover, we propose that irreversible cell activation may require several ligands to avoid activation by single, mislocalized signaling molecules.

Original languageEnglish
Pages (from-to)1855-1863
Number of pages9
JournalBiophysical Journal
Issue number8
Publication statusPublished - 2011 Apr 20

ASJC Scopus subject areas

  • Biophysics


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