Zu X W, Jay F T
Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.
J Biol Chem. 1991 Apr 5;266(10):6023-6.
Eight neutralizing monoclonal antibodies (mAbs) directed against the human interferon gamma (HuIFN-gamma) that were classified in the E1 epitope group were mapped by the synthetic peptide approach. A set of 136 octapeptide homologs of the 143-residue primary sequence of the HuIFN-gamma, each one with a 7-residue sequence overlap with successive peptide, was synthesized. Based on the similar reactivity patterns of all the mAbs with this set of synthetic peptides, the E1 functional epitope was localized to residues 84-94 on the HuIFN-gamma. The epitope sequence is: Ser-Asn-Lys-Lys-Lys-Arg-Asp-Asp-Phe-Gln-Lys. The fact that eight independently isolated mAbs binding to the same domain can neutralize the HuIFN-gamma activity suggests that the E1 domain must be at or adjacent to a functional site. Within this domain is a sequence element, Lys-Lys-Lys-Arg, that resembles the nuclear location signals known to effect the intracellular transportation of a number of nuclear proteins, such as the large tumor antigen (T antigen) of simian virus 40 (SV40) and polyoma virus and steroid hormone receptors. This observation suggests that the HuIFN-gamma molecule and/or its complex with the receptor must function in the nucleus to effect transcription regulation that results in the various biological activities. The signal for that intracellular transportation must be provided by the HuIFN-gamma molecule.
采用合成肽方法对8种针对人干扰素γ（HuIFN-γ）的中和单克隆抗体（mAb）进行了定位，这些抗体属于E1表位组。合成了一组136个八肽同系物，它们对应于HuIFN-γ 143个残基的一级序列，每个八肽与相邻肽有7个残基的序列重叠。基于所有mAb与这组合成肽的相似反应模式，E1功能表位被定位到HuIFN-γ的84-94位残基上。表位序列为：Ser-Asn-Lys-Lys-Lys-Arg-Asp-Asp-Phe-Gln-Lys。8个独立分离的结合同一结构域的mAb能够中和HuIFN-γ活性，这一事实表明E1结构域必定位于功能位点或与之相邻。在该结构域内有一个序列元件Lys-Lys-Lys-Arg，它类似于已知能影响许多核蛋白细胞内运输的核定位信号，如猴病毒40（SV40）和多瘤病毒的大肿瘤抗原（T抗原）以及类固醇激素受体。这一观察结果表明，HuIFN-γ分子和/或其与受体的复合物必定在细胞核中发挥作用以实现转录调控，从而产生各种生物学活性。这种细胞内运输的信号必定由HuIFN-γ分子提供。
