Phospholipase C activity in platelets from Bernard-Soulier syndrome patients.
The levels of glycoprotein (GP) Ib and GPV and phospholipase C activity were measured in platelets from three Bernard-Soulier syndrome patients. The patients' platelets had 46%, 46%, and 24% of control levels of GPIb alpha and 43%, trace, and 13% of control levels of GPV as determined by immunoblot analysis. Stimulation by thrombin, trypsin, the thromboxane analogue U46619, and the combination of U46619 and trypsin caused the formation of [32P]phosphatidic acid, an index of phospholipase C activity, in [32P]orthophosphate-prelabeled platelets. With all agonists, however, the formation of [32P]phosphatidic acid was markedly reduced in Bernard-Soulier syndrome platelets compared with control platelets. These data indicated a postreceptor defect in phospholipase C activation in Bernard-Soulier syndrome platelets and confirmed earlier observations of potential proteolytic and nonproteolytic mechanisms of platelet activation.
McNicol
A
A
Manitoba Institute of Cell Biology, Winnipeg, Canada.
Drouin
J
J
Clemetson
K J
KJ
Gerrard
J M
JM
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001606:Bernard-Soulier Syndrome / Q000201:enzymology*; D001792:Blood Platelets / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D015151:Immunoblotting; D010712:Phosphatidic Acids / Q000097:blood; D010740:Phospholipases / Q000097:blood*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
D010712:Phosphatidic Acids; D010980:Platelet Membrane Glycoproteins; D011450:Prostaglandin Endoperoxides, Synthetic; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D010740:Phospholipases; D014357:Trypsin; D013917:Thrombin