PROTEINS IMPORTANT FOR PROGRAMMED CELL DEATH AND FOR GENE-LINKED BLINDNESS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 细胞凋亡抑制因子(IAPs)是一种能阻断细胞死亡的抗凋亡因子。IAP含有蛋白质-蛋白质相互作用结构域和一个赋予E3泛素连接酶活性的C-末端环区。小分子拮抗剂与细胞IAP的结合促进了CIAP的自身泛素化和随后的蛋白酶体降解，从而释放了CIAP对细胞凋亡的抑制--这种情况可能会使一些癌症治疗更有效。远距离拮抗剂结合事件如何影响物理上不同的环区的E3连接酶活性尚不清楚。我们的初步数据支持这样一种假设，即拮抗剂结合导致结构重排，从而允许形成活性的环-环二聚体。此外，拮抗剂还可以促进中等大小的cIAP1群体；比单体大，但比二聚体小。这种形式的cIAP1在特定单价拮抗剂存在的情况下是优势物种，可能代表蛋白质的开放形式，但不是二聚体。我们从没有和存在小分子拮抗剂的情况下从cIAP1获得SAXS数据。HTRA1是一种多结构域的蛋白酶。人类HTRA1基因的变异促进了过度表达，增加了老年性黄斑变性的易感性。HTRA1由四个结构域组成，其分子形状已知，其蛋白酶活性需要形成一个1440个氨基酸的非共价同源三聚体。非蛋白酶域的功能作用尚不清楚。由IGFBP-RP结构域和Kazal结构域组成的N-末端结构域在两种同系物中缺失，表明其具有独特的调控功能。我们的目标是了解三聚体中的结构域位置、潜在的结构域相互作用和结构域齐聚状态。此外，我们还发现了可能有助于SAXS分析的抗HTRA1抗体片段。

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. Inhibitors of apoptosis (IAPs) are anti-apoptotic factors that block cell death. IAPs contain protein-protein interaction domains and a C-terminal RING domain that confers E3 ubiquitin ligase activity. Binding of small molecule antagonists to cellular IAPs promotes cIAP auto-ubiquitination and subsequent proteasomal degradation, thereby releasing cIAP inhibition of apoptosis?a situation that may render some cancer therapies more effective. How the distant antagonist binding event influences the E3 ligase activity of the physically distinct RING domain is unclear. Our preliminary data support a hypothesis where antagonist binding leads to a structural rearrangement that permits formation of active RING-RING dimers. Moreover, antagonists can also promote a cIAP1 population of intermediate size; larger than monomer, yet smaller than a dimer. This form of cIAP1 is the dominant species in the presence of a particular monovalent antagonist and may represent the ?open?, but un-dimerized, form of the protein. We seek SAXS data from cIAP1 both in the absence and presence of small molecule antagonists. Htra1 is a multi-domain protease. A variant human Htra1 gene promotes overexpression and increases susceptibility to age-related macular degeneration. Htra1 is composed of four domains for which molecular shapes are known by homology and its protease activity requires formation of a non-covalent homotrimer of 1440 amino acids. The functional roles of the non-protease domains are not clear. The N-terminal domain composed of the IGFBP-rP and Kazal domains is absent in baterial homologues, suggesting a unique regulatory function. Our objective is to learn the domain locations in the trimer, potential domain interactions and domain oligomerization status. In addition, we have anti-Htra1 antibody fragments which may aid in SAXS analysis.