Urban R G, Chicz R M, Strominger J L
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
J Exp Med. 1994 Aug 1;180(2):751-5. doi: 10.1084/jem.180.2.751.
The predominant peptides bound to major histocompatibility complex class II molecules expressed on human B cells are derived from a relatively limited number of self proteins. To determine whether any of the prebound self peptides might be released in endosomes during recycling, water-soluble HLA-DR1 molecules were incubated with a high affinity synthetic peptide at pH 4.0 and 7.0 at 37 degrees C. The resulting bound peptide repertoire was then acid extracted, and separated by reversed-phase high performance liquid chromatography. Using a combination of mass spectrometry and ultraviolet spectroscopy, prebound self peptides and newly bound synthetic peptide were characterized. Most self peptides bound to HLA-DR1 were not appreciably released during extended exposure to pH 4.0. However, some invariant chain-derived peptides were uniquely released at this pH.
与人类B细胞上表达的主要组织相容性复合体II类分子结合的主要肽段来源于相对有限数量的自身蛋白质。为了确定在循环过程中是否有任何预先结合的自身肽段可能在内体中释放，将水溶性HLA-DR1分子与高亲和力合成肽在37℃、pH 4.0和7.0条件下孵育。然后对所得结合肽库进行酸提取，并通过反相高效液相色谱进行分离。使用质谱和紫外光谱相结合的方法，对预先结合的自身肽段和新结合的合成肽段进行了表征。在长时间暴露于pH 4.0的过程中，大多数与HLA-DR1结合的自身肽段没有明显释放。然而，一些恒定链衍生肽段在该pH值下被独特地释放出来。
