Thromb Haemost 1997; 77(01): 143-149
DOI: 10.1055/s-0038-1655922
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Schattauer GmbH Stuttgart

Lateral Mobility of Integrin αIIbβ3 (Glycoprotein IIb/IIIa) in the Plasma Membrane of a Human Megakaryocyte

Annelies Schootemeijer
1   The department of Haematology, University Hospital Utrecht, The Netherlands
,
Gijsbert van Willigen
1   The department of Haematology, University Hospital Utrecht, The Netherlands
,
Hans van der Vuurst
1   The department of Haematology, University Hospital Utrecht, The Netherlands
,
Leon G J Tertoolen
2   Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
,
Siegfried W De Laat
2   Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
,
Jan-Willem N Akkerman
1   The department of Haematology, University Hospital Utrecht, The Netherlands
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Publikationsverlauf

Received 31. Oktober 1995

Accepted 18. September 1996

Publikationsdatum:
11. Juli 2018 (online)

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Summary

The migration of integrins to sites of cell-cell and cell-matrix contact is thought to be important for adhesion strengthening. We studied the lateral diffusion of integrin αIIbβ3 (glycoprotein Ilb/IIIa) in the plasma membrane of a cultured human megakaryocyte by fluorescence recovery after photobleaching of FITC-labelled monovalent Fab fragments directed against the P3 subunit. The diffusion of P3 on the unstimulated megakaryocyte showed a lateral diffusion coefficient (D) of 0.37 X10'9 cm2/s and a mobile fraction of about 50%. Stimulation with ADP (20 μM) or α-thrombin (10 U/ml) at 22° C induced transient decreases in both parameters reducing D to 0.21 X 10‘9 cm2/s and the mobile fraction to about 25%. The fall in D was observed within 1 min after stimulation but the fall in mobile fraction showed a lag phase of 5 min. The lag phase was absent in the presence of Calpain I inhibitor, whereas cytochalasin D completely abolished the decrease in mobile fraction. The data are compatible with the concept that cell activation induces anchorage of 50% of the mobile αIIbβ3 (25% of the whole population of receptor) to the cytoplasmic actin filaments, although, as discussed, other rationals are not ruled out.