CALNEXIN AND CLASS I MHC FUNCTION

描述(改编自调查人员的摘要)：I类专业 组织相容性分子在识别抗原方面起着关键作用 CD8+T淋巴细胞术。通过结合内质网中的多肽和 将它们运输到细胞表面，I类分子允许T淋巴细胞 扫描蛋白质的异常表达。这样就可以消除 癌细胞或被细胞内病原体感染的细胞。多肽 单个I类分子的结合裂隙在形状上差别很大。 和多肽含量。这种多样性使T淋巴细胞能够广泛地研究 抗原的多样性，并表明多肽结合的特异性是 主要受I类结合裂隙的形状控制。如何使用多肽 在体内与I类分子的结合目前还不清楚，而且 与辅助蛋白的相互作用会影响这一过程。有几个 辅助蛋白对生物发生和多肽结合特性的影响 细胞内的I类分子，最终目标是操纵 将对抗原呈递情况进行调查。1)基因多态对植物生长发育的影响 I类分子与钙粘蛋白和钙网蛋白的结合将被检测到。 研究人员此前发现了两种人类I类蛋白，编码 A*0201和B*0702分别与钙粘连蛋白弱结合和强结合。一个 另外16条人类白细胞抗原-A、-B和-C重链将被研究以 确定是否可以辨别绑定的模式，以及是否强烈和 弱粘结剂具有不同的传输动力学。2)职位 葡聚糖依赖于I类重链结合钙粘连蛋白和 将进行钙网硬蛋白检测。将引入新的葡聚糖受体位点 通过定点突变进入携带突变的I类重链 这阻止了它们的糖基化和与Calnexin的结合。3)I类如何 分子与TAP/TAPASIN结合，参与多肽的转运 将测定内质网。中潜在的交互站点 A*0201和B*0702包括部分a2和a3结构域，以及 多肽结合裂隙。4)钙粘蛋白与配体结合的重要区域 将通过突变后的突变克隆的转染来鉴定 进入钙粘连蛋白阴性的人类细胞NKR。已经有几种分析方法 确定Calnexin突变体是否具有功能。

DESCRIPTION (Adapted from the investigator's abstract): Class I major histocompatibility molecules play a key role in recognition of antigens by CD8+ T lymphoctyes. By binding peptides in the endoplasmic reticulum and transporting them to the cell surface, class I molecules allow T lymphocytes to scan for abnormal protein expression. This allows elimination of cancerous cells or cells infected with intracellular pathogens. The peptide binding clefts of individual class I molecules differ drastically in shape and peptide content. Such diversity allows T lymphocytes to survey a wide variety of antigens, and suggests that specificity of peptide binding is controlled largely by the shape of the class I binding cleft. How peptides bind to class I molecules in vivo is presently not well understood, and interactions with accessory proteins influence the process. How several accessory proteins influence the biogenesis and peptide binding properties of class I molecules within cells, with the eventual goal of manipulating antigen presentation will be investigated. 1) The effect of polymorphism in class I molecules on binding to calnexin and calreticulin will be examined. The investigators previously showed that two human class I proteins, encoded by A*0201 and B*0702, bind weakly and strongly to calnexin respectively. A panel of sixteen additional HLA-A, -B and -C heavy chains will be studied to determine if patterns of binding can be discerned, and whether strong and weak binders have different kinetics of transport. 2) The position dependence of the glycan on class I heavy chains for binding calnexin and calreticulin will be tested. Novel glycan acceptor sites will be introduced by site directed mutagenesis into class I heavy chains carrying a mutation which prevents their glycosylation and binding to calnexin. 3) How class I molecules bind to TAP/tapasin involved in transporting peptides into the endoplasmic reticulum will be determined. Potential sites of interaction in A*0201 and B*0702 include parts of the a2 and a3 domains, as well as the peptide binding cleft. 4) Regions of calnexin important for ligand binding will be identified by mutagenesis followed by transfection of mutant clones into the calnexin negative human cell, NKR. Several assays have been established to determine whether calnexin mutants are functional.