Relationship between intracellular calcium-dependent process and protein-tyrosine phosphorylation in human platelets: studies of platelets from a patient with defective A23187-induced platelet aggregation.
We had postulated that in a patient with defective calcium ionophore (A23187)-induced platelet aggregation, whose platelets showed normal intracellular Ca2+ mobilization in either the presence or absence of extracellular Ca2+ in response to A23187. A defect was present in an intracellular calcium-dependent process. We have now investigated whether the agonist-induced protein-tyrosine phosphorylation (PTP) was altered. Protein-tyrosine phosphorylation (PTP)-induced by A23187 in the patient's platelets was greatly diminished but that induced by thrombin was almost normal. These results suggest that an intracellular calcium-dependent process plays a fundamental role in A23187-induced PTP, whereas it does not in thrombin-induced PTP.
Fuse
I
I
First Department of Internal Medicine, Niigata University School of Medicine, Japan.
Higuchi
W
W
Uesugi
Y
Y
Hattori
A
A
Aizawa
Y
Y
D001791:Blood Platelet Disorders / Q000097:blood; D001792:Blood Platelets / Q000737:chemistry / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood*; D005110:Extracellular Space / Q000737:chemistry; D006801:Humans; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000097:blood / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology / Q000627:therapeutic use
D000001:Calcimycin; D011505:Protein-Tyrosine Kinases; D013917:Thrombin; D002118:Calcium