Hobbs M V, Morgan E L, Houghten R A, Thoman M L, Weigle W O
J Immunol. 1987 Apr 15;138(8):2581-6.
The synthetic peptide p23, representing residues 335 to 357 in the Fc region of human IgG1, was previously shown to induce Ig secretion in murine spleen cell cultures. In this report, overlapping peptides based on the sequence of p23 were synthesized to further map the active site in this molecule. The results from these studies indicate that leu-pro-pro-ser-arg (residues 351 to 355) retained the B cell differentiation-inducing properties of p23; however, expression of activity by this sequence was markedly influenced by N-flanking sequences. By using T cell-depleted spleen cell cultures, it was determined that at least two signals are required for p23-induced Ig secretion: one supplied by p23 directly and one supplied by a T cell-replacing factor present in p23-conditioned spleen cell supernatants. Both signals were mapped into the sequence leu-pro-pro-ser-arg. However, the latter signal, but not the former signal, again appeared to be influenced by sequences proximal to the active site. These data indicate that although the leu-pro-pro-ser-arg sequence is able to provide both required signals for p23-induced Ig secretion in spleen cell cultures, there may be subtle differences in how the cell types involved in this response interact with and/or are activated by this sequence.
合成肽p23代表人类IgG1 Fc区域中的335至357位氨基酸残基，先前已证明其可在小鼠脾细胞培养物中诱导Ig分泌。在本报告中，合成了基于p23序列的重叠肽，以进一步定位该分子中的活性位点。这些研究结果表明，亮氨酸-脯氨酸-脯氨酸-丝氨酸-精氨酸（351至355位氨基酸残基）保留了p23的B细胞分化诱导特性；然而，该序列的活性表达受到N侧翼序列的显著影响。通过使用去除T细胞的脾细胞培养物，确定p23诱导的Ig分泌至少需要两个信号：一个由p23直接提供，另一个由p23预处理的脾细胞上清液中存在的T细胞替代因子提供。两个信号都定位在亮氨酸-脯氨酸-脯氨酸-丝氨酸-精氨酸序列中。然而，后一个信号而非前一个信号似乎再次受到活性位点近端序列的影响。这些数据表明，尽管亮氨酸-脯氨酸-脯氨酸-丝氨酸-精氨酸序列能够为脾细胞培养物中p23诱导的Ig分泌提供所需的两个信号，但参与该反应的细胞类型与该序列相互作用和/或被其激活的方式可能存在细微差异。
