RELEASE OF PLATELET FIBRONECTIN (COLD-INSOLUBLE GLOBULIN) FROM ALPHA-GRANULES INDUCED BY THROMBIN OR COLLAGEN - LACK OF REQUIREMENT FOR PLASMA FIBRONECTIN IN ADP-INDUCED PLATELET-AGGREGATION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 54 (1), 8-12
Abstract
Platelets lysed with Triton X-100 contain 3.44 .+-. 1.27 (SD) .mu.g of fibronectin (cold-insoluble globulin) per 109 platelets. Fibronectin was partially released from washed whole platelets by collagen or thrombin, and its release by collagen was inhibited by aspirin. Analysis of subcellular fractions obtained by density-gradient centrifugation of disrupted platelets indicated that fibronectin was contained in the .alpha. granules. Fibrinogen depleted of fibronectin (< 2 .mu.g/ml) supported ADP-induced aggregation as effectively as fibrinogen contaminated with this protein, reinforcing the generally held view that fibrinogen itself is the necessary protein cofactor in this reaction.