Glycoproteins VI and Ib-IX-V stimulate tyrosine phosphorylation of tyrosine kinase Syk and phospholipase Cgamma2 at distinct sites.
Glycoproteins VI and Ib-IX-V stimulate tyrosine phosphorylation of tyrosine kinase Syk and phospholipase Cgamma2 at distinct sites.
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糖蛋白 VI 和 Ib-IX-V 在不同位点刺激酪氨酸激酶 Syk 和磷脂酶 Cgamma2 的酪氨酸磷酸化。
DOI：
10.1042/bj20031430
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Watson,SteveP
中科院分区：
文献类型：
--
作者：
Suzuki-Inoue,Katsue;Wilde,JonathanI;Andrews,RobertK;Auger,JocelynM;Siraganian,ReubenP;Sekiya,Fujio;Rhee,SueGoo;Watson,SteveP
Glycoproteins GPVI and GPIb-IX-V stimulate robust tyrosine phosphorylation of Syk and PLCγ2 (phospholipase Cγ2) in washed platelets, but only the former stimulates pronounced activation of phospholipase. Using phospho-specific antibodies, we demonstrate that GPVI, but not GPIb-IX-V, stimulates significant tyrosine phosphorylation of Syk at the autophosphorylation site pY525/526, a marker of Syk activity. In addition, GPVI stimulates tyrosine phosphorylation of PLCγ2 at Tyr753and Tyr759, whereas GPIb-IX-V only induces significant phosphorylation at Tyr753. Both receptors stimulate tyrosine phosphorylation of Btk at the regulatory Tyr223and Tyr551. Syk and Btk phosphorylate peptides from PLCγ2 containing Tyr753and Tyr759respectively, suggesting that they may stimulate phosphorylation at these sites in phospholipase. Studies using PLCγ2-deficient platelets demonstrated that phospholipase is not required for the activation of integrin αIIbβ3 by GPIb-IX-V. Our results demonstrate fundamental differences between GPVI and GPIb-IX-V in the regulation of tyrosine phosphorylation of Syk and PLCγ2 consistent with the functional impairment of phospholipase in signalling by GPIb-IX-V.
