Other related notes Flashcards
Key proteins involved in platelet activation
G proteins (guanine nucleotide-binding proteins)
Function of G proteins in platelet activation
Stimulate eicosanoid synthesis and IP3-DAG pathways”
Two pathways stimulated by G proteins during platelet activation
Eicosanoid synthesis and IP3-DAG pathways
Platelet activation pathways controlled by G proteins
Eicosanoid synthesis and IP3-DAG
Eicosanoid synthesis pathway also known as
Prostaglandin, cyclooxygenase, or thromboxane pathway
Eicosanoids are derived from
Arachidonic acid or a similar fatty acid
Examples of eicosanoids
Prostacyclin, thromboxane
Receptors activated by collagen, ADP, thrombin, and epinephrine
Phospholipase A2
Phospholipase A2 releases
Arachidonic acid from phosphatidylinositol
Enzymes that act on arachidonic acid in platelet activation
Cyclooxygenase, peroxidase, thromboxane synthase
Thromboxane A2 (TXA2) function in platelet activation
Activates platelet, suppresses adenylate cyclase, reduces cAMP
Role of ionic calcium in platelet activation
Supports actin microfilament contraction
Eicosanoid pathway in endothelial cells vs platelets
Endothelial cells have prostacyclin synthase; platelets have thromboxane synthase
Eicosanoid pathway result in endothelial cells
Prostaglandin I2 (prostacyclin)
Prostacyclin function on platelets
Binds to IP receptor, accelerates adenylate cyclase, increases cAMP
Effect of prostacyclin on ionic calcium
Sequesters ionic calcium to the DTS
Function of endothelial eicosanoid pathway in intact blood vessels
Suppresses platelet activation
Activation of IP3-DAG pathway
G-protein activates phospholipase C
Phospholipase C function in IP3-DAG pathway
Cleaves phosphatidylinositol 4,5-bisphosphate to form IP3 and DAG
Function of IP3 in platelet activation
Promotes release of ionic calcium from DTS, activates actin microfilament contraction
IP3 effect on phospholipase A2
IP3 may activate phospholipase A2
Role of DAG in platelet activation
Activates phosphokinase C, triggers phosphorylation of pleckstrin