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p-155, a multimeric platelet protein that is expressed on activated platelets.
C P Hayward1, J W Smith, P Horsewood
1Department of Medicine, McMaster University Medical Centre, Hamilton, Ontario, Canada.
The Journal of Biological Chemistry
|April 15, 1991
Summary
Researchers identified a novel platelet protein, p-155, released upon activation. This activation-dependent protein binds to platelets and is distinct from other known platelet glycoproteins, though its function remains unknown.
Area of Science:
- Hematology
- Molecular Biology
- Biochemistry
Background:
- Platelets undergo significant biochemical and morphological changes upon activation.
- These changes are crucial for physiological processes like adhesion, aggregation, and coagulation.
- Platelet activation leads to alterations recognized by specific monoclonal antibodies.
Purpose of the Study:
- To characterize a novel platelet activation-dependent protein recognized by the JS-1 monoclonal antibody.
- To determine the molecular properties and identity of this newly identified protein, designated p-155.
- To investigate the release and binding characteristics of p-155 during platelet activation.
Main Methods:
- Monoclonal antibody recognition (JS-1) and immunoprecipitation.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for molecular weight determination.
- Isoelectric focusing, immunodepletion, and immunoblotting to distinguish p-155 from other proteins.
- Triton X-114 phase separation, membrane elution, and analysis of platelet releasate to assess protein solubility and localization.
- Radioimmunoprecipitation and direct binding assays to confirm activation-dependent expression.
Main Results:
- A novel platelet glycoprotein, p-155, was identified, characterized by its release upon activation and binding to the activated platelet surface.
- p-155 exists as disulfide-bonded multimers in its native state and has a distinct reduced molecular weight.
- Distinguished from glycoprotein Ia, von Willebrand factor, and thrombospondin using various biochemical and immunological techniques.
- Evidence suggests p-155 is a soluble, non-integral membrane-associated protein found in platelet releasate.
- Its presence was specific to activated platelets and not detected in other blood cells or tissues.
Conclusions:
- p-155 is a unique, activation-dependent protein released by platelets.
- Its distinct molecular characteristics differentiate it from known platelet glycoproteins.
- Further research is needed to elucidate the specific functional role of p-155 in platelet biology.