Epstein-Barr virus latent membrane protein 2 associates with and is a substrate for mitogen-activated protein kinase
Epstein-Barr virus latent membrane protein 2 associates with and is a substrate for mitogen-activated protein kinase
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DOI：
10.1128/jvi.71.6.4752-4760.1997
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发表时间：
1997-06-01
影响因子：
5.4
通讯作者：
Rowe, DT
中科院分区：
文献类型：
--
作者：
Panousis, CG;Rowe, DT
EB病毒潜伏膜蛋白2（LMP 2）通过免疫球蛋白（IG）受体干扰B淋巴细胞信号转导。LMP 2有两种亚型，不同之处仅在于一种亚型（LMP 2a）含有一个N-末端胞质结构域，而另一种亚型则没有。LMP 2a是在胞质结构域中的酪氨酸和丝氨酸上磷酸化的磷蛋白。GST 1 -119是一种谷胱甘肽S转移酶（GST）融合蛋白，含有胞质结构域的119个氨基酸，从BJAB细胞提取物中亲和沉淀丝氨酸激酶活性。亲和沉淀的激酶磷酸化LMP 2a序列，和激酶活性增加诱导后。亲和沉淀蛋白质的Western免疫印迹的探测表明，Erk 1形式的丝裂原活化蛋白激酶（MAPK）的存在。纯化的MAPK磷酸化GST融合蛋白含有LMP 2a的胞质结构域和突变分析用于鉴定S15和S102作为体外磷酸化位点。制备针对麦芽糖结合蛋白-LMP 2a胞质结构域融合蛋白（MBP 1 -119）的多克隆兔抗血清，并用于免疫沉淀来自体外永生化淋巴母细胞样B细胞系B 95 - 8 CR的LMP 2a。来自B 95 - 8 CR的LMP 2a免疫沉淀物含有作为共沉淀蛋白的MAPK。交联B 95 - 8 CR细胞表面的IG不能诱导细胞内MAPK活性。用佛波醇肉豆蔻酸酯乙酸酯（PMA）处理B 95 - 8 CR能够绕过IG受体阻滞并激活MAPK活性。PMA诱导后LMP 2a丝氨酸残基的磷酸化增加。LMP 2a丝氨酸磷酸化的MAPK在控制潜伏期的可能作用进行了讨论。
The latent membrane protein 2 (LMP2) of Epstein-Barr virus interferes with B-lymphocyte signal transduction through the immunoglobulin (Ig) receptor. Two isoforms of LMP2 exist and differ only in that one isoform (LMP2a) contains an N-terminal cytoplasmic domain that the other isoform does not. LMP2a is a phosphoprotein that is phosphorylated on tyrosines and serines in the cytoplasmic domain. GST1-119, a glutathione S transferase (GST) fusion protein containing the 119 amino acids of the cytoplasmic domain, affinity precipitated serine kinase activity from BJAB cell extracts. The affinity-precipitated kinase phosphorylated LMP2a sequences, and kinase activity was increased following induction. Probing of Western immunoblots of affinity-precipitated proteins showed that the Erk1 form of mitogen-activated protein kinase (MAPK) was present. Purified MAPK phosphorylated GST fusion proteins containing the cytoplasmic domain of LMP2a and mutational analyses were used to identify S15 and S102 as the sites of in vitro phosphorylation. A polyclonal rabbit antiserum was prepared against a maltose binding protein-LMP2a cytoplasmic domain fusion protein (MBP1-119) and used to immunoprecipitate LMP2a from the in vitro-immortalized lymphoblastoid B-cell line B95-8CR. LMP2a immunoprecipitates from B95-8CR contained MAPK as a coprecipitated protein. Cross-linking surface Ig on B95-8CR cells failed to induce MAPK activity within the cells. Treatment of B95-8CR with phorbol myristate acetate (PMA) was able to bypass the Ig receptor block and activate MAPK activity. Phosphorylation of LMP2a on serine residues increased after PMA induction. The possible role for LMP2a serine phosphorylation by MAPK in the control of latency is discussed.