章b淋巴細胞的活化與抗體產(chǎn)生-資料下載頁
2025-04-30 04:27本頁面
【正文】 ated kinases accumulate under the membrane in close proximity to the cytoplasmic domains of the TcR CD3 plex CD4 MHC II MHC II CD45 TCR binds MHCpeptide antigen phosphatase CD45 activates kinases such as Fyn P Early T cell activation The tyrosine kinase ZAP70 binds to the phosphorylated ITAMs of CD3z further activation requires ligation of the coreceptor, CD4 Zap70 Fyn phosphorylates the ITAMs of CD3g, d, e and z ITAMS Lck Fyn CD4 CD45 P MHC II T cell activation Lck Fyn P MHC II Zap70 T cell activation Binding of CD4 coreceptor to MHC class II brings Lck into the plex, which then phosphorylates and activates ZAP70 Tyrosine rich cell membrane associated Linker of Activation in T cells (LAT) and SLP76 associate with cholesterolrich lipid rafts LAT SLP76 Activated ZAP70 phosphorylates LAT amp。 SLP76 P P P P ZAP70 phosphorylates LAT and SLP76 T cell activation Lck Fyn P MHC II Zap70 LAT SLP76 P P P P SLP76 binds Tec kinases and activates phospholipase C g (PLCg) Tec Tec PLCg cleaves phosphotidylinositol bisphosphate (PIP2) to yield diacylglycerol (DAG) and inositol trisphosphate (IP3) Activated ZAP70 phosphorylates Guaninenucleotide exchange factors (GEFS) that in turn activate the small GTP binding protein Ras Ras activates the MAP kinase cascade ? IP3途徑：活化 NFAT ? DAG途徑：活化 NFΚB ? Ras/Rac途徑： 活化 AP1 ——誘導 IL2等 基因的轉(zhuǎn)錄 ? 第二信號的轉(zhuǎn)導 – Rac——MAPK途徑 ——Jnk——junfos——AP1 ——延長 IL2 mRNA的壽命 二、 B細胞活化信號的轉(zhuǎn)導 ? 發(fā)送第一信號的是 Igα Igβ ? BCR交聯(lián)后早期 PTK為 blk,fyn或 lyn ? SYK代替 ZAP70 ? 活化的轉(zhuǎn)錄因子和表達的基因不同
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