Related Experiment Videos
Glycoprotein IIIa is phosphorylated in intact human platelets
L V Parise1, A B Criss, L Nannizzi
1Gladstone Foundation Laboratories for Cardiovascular Disease, University of California, San Francisco.
Blood
|June 15, 1990
Summary
Platelet glycoprotein IIb-IIIa (GP IIb-IIIa) function is regulated by phosphorylation of GP IIIa. This phosphorylation increases during platelet activation, suggesting a role for protein kinase C in GP IIb-IIIa regulation.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- The glycoprotein IIb-IIIa complex (GP IIb-IIIa) is crucial for platelet aggregation and other functions.
- Mechanisms regulating GP IIb-IIIa during platelet activation remain largely unknown.
- Phosphorylation is a known regulatory mechanism for other cell receptors.
Purpose of the Study:
- To investigate the role of phosphorylation in regulating glycoprotein IIb-IIIa (GP IIb-IIIa) function during platelet activation.
- To identify which subunit of GP IIb-IIIa is phosphorylated and the conditions that affect its phosphorylation.
Main Methods:
- Utilized 32P-labeled platelets to detect and quantify protein phosphorylation.
- Activated platelets with thrombin or phorbol 12-myristate 13-acetate (PMA).
- Used prostacyclin and staurosporin to inhibit platelet activation and protein kinase C, respectively.
Main Results:
- Glycoprotein IIIa (GP IIIa), but not GP IIb, was phosphorylated, primarily on threonine residues.
- GP IIIa phosphorylation increased four-fold upon activation with thrombin or PMA.
- Prostacyclin inhibited GP IIIa phosphorylation, while staurosporin blocked the thrombin-induced increase.
Conclusions:
- Platelet activation leads to increased phosphorylation of GP IIIa, likely mediated by protein kinase C.
- This phosphorylation event may play a regulatory role in glycoprotein IIb-IIIa (GP IIb-IIIa) complex function.
- Further research is warranted to elucidate the specific regulatory impact of GP IIIa phosphorylation on GP IIb-IIIa activity.