A NOVEL PROTEIN COMPLEX REQUIRED FOR ENDOSOMAL SORTING OF MEMBRANE TRANSPORTERS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 内吞作用后分选至溶酶体是下调细胞表面受体和转运蛋白丰度的关键机制。 在全基因组化学遗传筛选中，我们发现了一个特征不明显的S。酿酒酵母蛋白是许多细胞表面蛋白的内体分选所需的。 在高等物种中也发现了潜在的同源物。 缺乏该基因的酵母菌株的表型表明内体囊泡的融合/对接缺陷。 该蛋白定位于细胞质以及内体。 在凝胶过滤实验中，细胞质池显示为均匀的650-kDa复合物。 我们假设细胞质复合物可能是内体结合形式的亚复合物。 因此，了解650-kD可溶性复合物的组成可能会导致更好地了解内体融合和对接的机制。 我们建议通过质谱法研究TAP纯化复合物的组成。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Endocytosis followed by sorting to the lysosome is a key mechanism for downregulating the abundance of cell surface receptors and transporters. In a genome-wide chemical genetic screen we have identified a poorly characterized S. cerevisiae protein that is required for endosomal sorting of many cell surface proteins. Potential homologs in higher species have also been identified. Phenotype of the yeast strain lacking this gene suggests a defect in fusion/docking of endosomal vesicles. The protein localizes to the cytoplasm as well as endosomes. The cytoplasmic pool appears as a homogenous, 650-kDa complex in gel filtration experiments. We hypothesize that the cytosolic complex may be a subcomplex of the endosome-bound form. Thus, understanding the composition of the 650-kD soluble complex may lead to a better understanding of the mechanism of endosome fusion and docking. We propose to study the composition of the TAP-purified complex by mass spectrometry.