Characterization of 85Kd protein tyrosine phosphorylated by erythropoietin stimulation

促红细胞生成素（Epo）通过与其受体（Epo- r）相互作用，是红细胞前体增殖和分化的主要调节因子。尽管Epo-r在其胞内结构域中缺乏酪氨酸激酶一致序列，但将其配体添加到Epo应答细胞UT-7/Epo中，可诱导145,130,80-85和40kd细胞蛋白的快速和短暂酪氨酸磷酸化。这些蛋白的酪氨酸磷酸化发生剂量和时间依赖性。我们发现酪氨酸磷酸化的145 Kd蛋白与PLC-_< γ bbb1相同。该蛋白的酪氨酸磷酸化在30秒内可检测到，几乎在1分钟达到最大值。这种感觉可以持续10分钟，之后就会减弱。此外，在Epo刺激的细胞中，PLC-_< γ >1与80-85和40 Kd蛋白发生物理关联，这些蛋白在Epo刺激下被酪氨酸磷酸化。我们试图鉴定80-85 Kd蛋白，发现该蛋白与P13K、Epo-R和Raf-1不相同。我们现在正试图鉴定这种蛋白质。

Erythropoietin (Epo) is the major regulator of the proliferation and differentiation of erythroid precursors through interaction with its receptor (Epo-R). Although Epo-R lacks a tyrosine kinase consensus sequence within its intracellular domain, the addition of its ligand to Epo-responsive cells, UT-7/Epo, induces the rapid and transient tyrosine phosphorylation of 145,130,80-85 and 40 Kd cellular proteins. Tyrosine phosphorylation of these proteins occurred dose- and time-dependently. We showed that the tyrosine phosphorylated 145 Kd protein is identical to PLC-_<gamma>1. Tyrosine phosphorylation of this protein is detectable within 30 seconds and almost reaches the maximum at 1 minute. This can last up to 10 minutes and declines thereafter. Additionally, in Epo-stimulated cells, PLC-_<gamma>1 become physically associated with 80-85 and 40 Kd proteins which have been tyrosine phosphorylated in response to Epo. We tried to identified the 80-85 Kd protein and found that this protein is not identical to P13K,Epo-R,nor Raf-1. We are now trying to identify this protein.