title: Annexin V relocates to the periphery of activated platelets following thrombin activation: an ultrastructural immunohistochemical approach.
abstract: 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.
authors.affiliation: School of Biochemistry and Molecular Biology, University of Leeds, UK.
authors.forename: E
authors.initials: E
authors.lastname: Tzima
authors.forename: C
authors.initials: C
authors.lastname: Poujol
authors.forename: P
authors.initials: P
authors.lastname: Nurden
authors.forename: A T
authors.initials: AT
authors.lastname: Nurden
authors.forename: M A
authors.initials: MA
authors.lastname: Orchard
authors.forename: J H
authors.initials: JH
authors.lastname: Walker
mesh_terms: D017304:Annexin A5 / Q000502:physiology* / Q000648:ultrastructure; D001692:Biological Transport; D001792:Blood Platelets / Q000502:physiology* / Q000648:ultrastructure*; D006801:Humans; D016253:Microscopy, Immunoelectron; D015539:Platelet Activation; D013917:Thrombin / Q000502:physiology*
chemical_list: D017304:Annexin A5; D013917:Thrombin