ANNEXIN V RELOCATES TO THE PERIPHERY OF ACTIVATED PLATELETS FOLLOWING THROMBIN ACTIVATION: AN ULTRASTRUCTURAL IMMUNOHISTOCHEMICAL APPROACH
✍ Scribed by Eleni Tzima; Christel Poujol; Paquita Nurden; Alan T Nurden; Margaret A Orchard; John H Walker
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 690 KB
- Volume
- 23
- Category
- Article
- ISSN
- 1065-6995
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✦ Synopsis
We have previously shown biochemically that the physiological agonist thrombin can cause translocation of endogenous annexin V to a fraction containing all platelet membranes. This paper reports ultrastructural immunohistochemical data revealing that annexin V molecules localize with plasma membranes of blood platelets following thrombin activation. When ultrathin sections of resting platelets were examined by immunogold staining, annexin V was found to be cytosolic, having a generalized distribution throughout the platelet. After thrombin activation, annexin V became peripheral in location and plasmalemma association increased. Morphometric analysis of gold particles shows that annexin V relocates specifically to the plasma membrane and its underlying cytoskeleton following treatment with thrombin. In control platelets 6.1% +/- 0.78 of annexin V is present at the plasma membrane and 15.0% +/- 0.82 in the region corresponding to the membrane cytoskeleton (10-80 nm); after stimulation with 0.5 unit/ml thrombin for 2 min this increased to 16.7% +/- 0.22 and 40.4% +/- 0.53, respectively.