Title: Thrombospondin
Additional Names: Glycoprotein G; thrombin-sensitive protein; TSP
Literature References: A major glycoprotein constituent of human platelet a-granules that is released in response to platelet activation by a-thrombin, and plays an important role in mediating platelet aggregation. Discovery and initial isoln and properties: N. L. Baenziger et al., Proc. Natl. Acad. Sci. USA 68, 240 (1971); eidem, J. Biol. Chem. 247, 2723 (1972). Thrombospondin was initially thought to be a single polypeptide of mol wt about 190,000, but has been shown to be a disulfide-linked trimer of mol wt 450,000: I. Hagen, Biochim. Biophys. Acta 392, 242 (1975); D. R. Phillips, P. P. Agin, J. Biol. Chem. 252, 2121 (1977); J. W. Lawler et al., Thromb. Haemostasis 37, 355 (1977); eidem, J. Biol. Chem. 253, 8609 (1978); S. S. Margossian et al., ibid. 256, 7495 (1981). Synthesis and secretion by cells in culture: G. J. Raugi et al., J. Cell Biol. 95, 351 (1982). Quantitative analysis: J. N. George et al., J. Lab. Clin. Med. 92, 430 (1978). The binding of secreted thrombospondin to platelet membranes is dependent on Ca2+: D. R. Phillips et al., J. Biol. Chem. 255, 11629 (1980). Evidence for calcium-sensitive structure: J. Lawler et al., ibid. 257, 12257 (1982). Radioimmunoassay: S. D. Saglio, H. S. Slayter, Blood 59, 162 (1982). Identity of thrombospondin with the endogenous lectin secreted by activated platelets: E. A. Jaffee et al., Nature 295, 246 (1982). See also Fibrinogen.
Properties: Partial specific volume: 0.714 ml/g. Intrinsic viscosity: 40 ml/g in buffered saline at pH 7.6, 20°. |