MHC GENES INVOLVED IN ANTIGEN PROCESSING & PRESENTATION

T淋巴细胞激活，从而启动免疫反应， 需要T细胞受体识别由多肽组成的复合体 与主要组织相容性复合体结合的外源抗原片段 (MHC)分子在抗原提呈细胞(APC)表面。尽管 免疫识别的第一步的关键性质是，很少 了解抗原处理的机制方面，例如如何 抗原片段是如何产生的，以及它们是如何产生的，以及它们在APC中的位置 遇到MHC分子。 越来越多的证据表明，MHC包含的基因 在将处理后的抗原运送到小泡中的作用 与MHC类分子及其后续分子结合的分泌系统 囊泡运输到细胞表面。两个MHC的最新克隆 被称为HAM1和HAM2的基因，它们与一个大的超家族 原核和真核转运蛋白都代表着重要的一步 有助于理解抗原加工的本质。这项建议 论述了这两个基因的结构和功能特征 基因。将进行两种类型的实验，以提供正式的证据 HAM1和HAM2基因在抗原加工中的作用。第一, 将全长、野生型HAM1和HAM2 cDNA导入细胞 携带MHC连锁突变的株系可使抗原处理失活 路径。其次，HAM1和HAM2表达不足的小鼠将是 通过将这些基因的缺陷拷贝引入胚胎干细胞而产生的 细胞通过同源重组，然后注入这些 将细胞改造成小鼠囊胚。为了进一步刻画 HAM1和HAM2基因产物的功能，会产生抗体 从推导出的氨基酸序列衍生出的合成肽。这 抗体将用于免疫组织化学定位相应的 细胞内的蛋白质(从而识别亚细胞隔间 在多肽与MHC分子相遇的地方)，并帮助它们的纯化。 将尝试在体外重建多肽运输 系统，并分析运输过程的特殊性。 此外，两个新的MHC的功能意义 类II基因将通过检测它们的多态和 通过产生抗体来识别相应的 基因产品。

T lymphocyte activation, and hence the initiation of an immune response, requires recognition by T cell receptors of complexes consisting of peptide fragments of foreign antigens bound to major histocompatibility complex (MHC) molecules on the surface of antigen presenting cells (APC). Despite the critical nature of this first step in immune recognition, little is known about the mechanistic aspects of antigen processing, such as how the antigen fragments are produced, and how and where within the APC they encounter MHC molecules. A growing body of evidence suggests that the MHC contains genes which function in the transport of processed antigen into vesicles of the secretory system for binding by MHC class molecules and subsequent vesicular transport to the cell surface. The recent cloning of two MHC genes, called HAM1 and HAM2, which are homologous to a large superfamily of both prokaryotic and eukaryotic transporters represents a major step towards understanding the nature of antigen processing. This proposal deals with the structural and functional characterization of these two genes. Two types of experiments will be done to provide formal proof of the involvement of the HAM1 and HAM2 gene in antigen processing. First, full length, wild type HAM1 and HAM2 cDNAs will be introduced into cell lines carrying MHC-linked mutations that inactivate the antigen processing pathway. Second, mice deficient in HAM1 and HAM2 expression will be produced by introducing defective copies of these genes into embryonic stem cells by homologous recombination, and subsequently injecting these modified cells into mouse blastocysts. In order to further characterize the function of the HAM1 and HAM2 gene products, antibody will be produced to synthetic peptides derived from the deduced amino acid sequences. This antibody will be used immunohistochemically to localize the corresponding proteins within the cell (thus identifying the subcellular compartment where peptide meets MHC molecule), and to aid in their purification. Attempts will be made to reconstitute peptide transport in in vitro systems, and to analyze the specificity of the transport process. In addition to the above, the functional significance of two novel MHC class II-like genes will be addressed by examining their polymorphism and by producing antibody which would allow identification of the corresponding gene products.