Observations on the “Cytoskeleton” of Human Platelets^[*]

Summary

Structural study of rapidly lysed platelets supports the view that that shape change involves a change in state of the microfilaments which contain actin. The microtubule “bundle” appears to be a continuous coil. Proteolysis of a high molecular weight band is observed in platelets which can no longer form filopodia after suppression by local anesthetics.

^* Presented at the VIth International Congress on Thrombosis and Haemostasis, Philadelphia, U.S.A.

• References

• 1 Behnke O, Kristensen I, Engdahl L. 1971; Electron microscopical observations on actinoid and myosinoid filaments in blood platelets. Journal of Ultrastructural Research 37: 351-369
• 2 Behnke O, Zelander T. 1967; Filamentous substructure of microtubules of the marginal bundle of mammalian blood platelets. Journal of Ultrastructural Research 19: 147-165
• 3 Bettex-Galland M, Lüscher EF. 1959; Extraction of an actomyosin-like protein from human thrombocytes. Nature (Lond.) 184: 276
• 4 Bettex-Galland M, Luscher EF, Weibel RR. 1969; Thrombosthenin-electron microscopical studies on its localization in human blood platelets and some properties of its subunits. Thrombosis et Diathesis Haemorrhagica 22: 431-449
• 5 Crawford N. 1977 Platelet microtubule subunit proteins. This volume
• 6 Hartwig JH, Stossel TP. 1975; Isolation and properties of actin, myosin, and a new actin- binding protein in rabbit alveolar macrophages. Journal of Biological Chemistry 250: 5695-5705
• 7 Ikeda Y, Steiner M. 1976; Isolation of platelet microbubule protein by an immunosorptive method. Journal of Biological Chemistry 251: 6135-6141
• 8 Laemmli UK. 1970; Cleavage of structural proteins during assembly of the head of bacteriophage T4. Nature (Lond.) 227: 680-685
• 9 Lucas RC, Detwiler TC, Stracher A. 1976; The identification and isolation of a high molecular weight (270,000 dalton) actin-binding protein from human platelets. Journal of Cell Biology 70: 259 a
• 10 Nachmias VT, Huxley HE, Kessler D. 1970; Electron microscope observations on actomyosin and actin preparations from Physarum polycephalum, and on their interaction with heavy meromyosin subfragment 1 from muscle myosin. Journal of Molecular Biology 50: 83-90
• 11 Nachmias V, Sullender J, Asch A. 1977; Effects of local anaesthetics on filopodial formation by human platelets. Blood 50: 39-53
• 12 Pollard TD. 1977 Platelet contractile proteins. This volume
• 13 Tilney LG, Hatano S, Ishikawa H, Mooseker MS. 1973; The polymerization of actin: its role in the generation of the acrosomal process of certain echinoderm sperm. Journal of Cell Biologv 59: 109-126
• 14 Tilney LG, Detmers P. 1975; Actin in erythrocyte ghosts and its association with spectrin. Evidence for a nonfilamentous form of these two molecules in situ. Journal of Cell Biology 66508-66520
• 15 White JG. 1971. Platelet microtubules and microfilaments: effects of cytochalasin B on structure and function. J.. (ed.) In: Platelet Aggregation. Caen, Masson, Cie. Pubs; Paris: p 15
• 16 Zucker-Franklin D. 1969; Microfibrils of blood platelets: their relationship to microtubules and the contractile protein. Journal of Clinical Investigation 48: 167-175