Platelets Interact with Soluble and Insoluble Collagens through Characteristically Different Reactions

Platelet interaction with soluble and insoluble collagens was characterized through binding studies. In contrast to resting platelets, cells reacted with activators, TS2/16 (integrin α2β1-activating antibody), thrombin, collagen-related peptide, or ADP, exhibited specific soluble collagen binding th...

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Bibliographic Details
Published in:The Journal of biological chemistry 1998-06, Vol.273 (24), p.14827-14837
Main Authors: Jung, Stephanie M., Moroi, Masaaki
Format: Article
Language:English
Subjects:
Animals
Antibodies - pharmacology
Blood Platelets - physiology
Calcium - pharmacology
Cattle
Collagen - metabolism
Epoprostenol - pharmacology
Humans
Integrins - immunology
Integrins - metabolism
Integrins - physiology
Kinetics
Magnesium - pharmacology
Membrane Glycoproteins - immunology
Platelet Activation - drug effects
Protein Binding - drug effects
Receptors, Collagen
Solubility
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Summary:Platelet interaction with soluble and insoluble collagens was characterized through binding studies. In contrast to resting platelets, cells reacted with activators, TS2/16 (integrin α2β1-activating antibody), thrombin, collagen-related peptide, or ADP, exhibited specific soluble collagen binding that is Mg2+-dependent, but inhibited by prostaglandin I2, Ca2+, and Gi9 (anti-integrin α2β1 antibody). Each platelet has 1500–3500 soluble collagen binding sites, with a dissociation constant of 3.5–9 × 10−8m. This is the first study to show the specific binding of soluble collagen to platelets; our data strongly suggest that the receptor is integrin α2β1 after it becomes activated upon platelet activation. These results suggest that activation of platelets transforms integrin α2β1 to a state with higher affinity binding sites for soluble collagen. The soluble collagen-platelet interaction was compared with the platelet interaction with fibrillar collagen, which has until now not been demonstrated to bind specifically to platelets. Here, we demonstrated specific, biphasic fibrillar collagen binding. One phase is rapid and metal ion-independent, and accounts for most of the binding. The other phase is slow and Mg2+-dependent. The characteristic differences in the specific bindings of soluble and fibrous collagens demonstrate the different contributions of two different collagen receptors.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.273.24.14827