Kawamoto S, Shoji M, Setoguchi Y, Kato M, Hashizume S, Ichikawa A, Osada K, Katakura Y, Tachibana H, Murakami H
Graduate School of Genetic Resources Technology, Kyushu University, Fukuoka, Japan.
Cytotechnology. 1995;17(2):103-8. doi: 10.1007/BF00749397.
The human monoclonal antibody AE6F4 specifically reacts with human lung cancer tissues but does not with normal tissues. This monoclonal antibody recognizes a cytosolic 31 kDa antigen in the cancer cells. In a previous study, we elucidated that the 31 kDa antigen belonged to a family of proteins collectively designated as 14-3-3 proteins, which were known as protein kinase-dependent activators of tyrosine/trytophan hydroxylases, or protein kinase C inhibitor proteins. Here we report molecular cloning of the 31 kDa antigen from the human lung adenocarcinoma cell line, A549. Sequencing analysis indicates that the cloned cDNA is identical to that of previously reported human placental cytosolic phospholipase A2 (cPLA2), which is also a member of the 14-3-3 protein family. Western analysis demonstrated that a 31 kDa recombinant cPLA2 expressed in monkey COS cells was recognized by the AE6F4 monoclonal antibody. Binding of the monoclonal antibody to the recombinant cPLA2 was abolished when treated with sodium periodate, suggesting that not only are carbohydrate chains associated with the cPLA2, but they also play a crucial role in antigen recognition by the monoclonal antibody.
人源单克隆抗体AE6F4能与人肺癌组织特异性反应，但与正常组织无反应。该单克隆抗体可识别癌细胞中的一种31 kDa胞质抗原。在先前的研究中，我们阐明该31 kDa抗原属于一类统称为14-3-3蛋白的蛋白质家族，这些蛋白是已知的酪氨酸/色氨酸羟化酶的蛋白激酶依赖性激活剂，或蛋白激酶C抑制蛋白。在此，我们报道了从人肺腺癌细胞系A549中克隆31 kDa抗原。测序分析表明，克隆的cDNA与先前报道的人胎盘胞质磷脂酶A2（cPLA2）相同，cPLA2也是14-3-3蛋白家族的成员。蛋白质免疫印迹分析表明，在猴COS细胞中表达的31 kDa重组cPLA2可被AE6F4单克隆抗体识别。用高碘酸钠处理后，单克隆抗体与重组cPLA2的结合被消除，这表明不仅碳水化合物链与cPLA2相关，而且它们在单克隆抗体的抗原识别中也起着关键作用。
