ID PHASES OF CN2 W/ IMAGEPLATES, XRAY DIFFRACTION AT HIGH PRESSURE & TEMPERATURE

本项目的重点是阐明其结构 分泌途径中的蛋白质。囊泡中的关键蛋白 形成是adp核糖化因子，它隔离蛋白质。 膜上形成囊泡所必需的。这种蛋白质表现为 就像开/关开关一样，GDP形式可溶于胞浆， GTP形式是膜相关的。其中一个要素是 膜结合所必需的是多花柱基团 蛋白质的N-末端，如果没有它，膜结合就不会 发生。到目前为止，人类ARF1的结构已经确定， 酵母ARF1和ARF2的结构正在进行中。除了……之外 ARF，细胞还含有与ARF相关的蛋白质，称为ARL， 似乎具有类似于ARF的功能，但并不完全相同。我们 已经从果蝇中结晶出ARL1，希望获得一种 结构，该结构可能指示ARL和ARF之间的区别 以及它们与细胞功能的关系。这些水晶也是 对于内部数据收集来说很小。在国际象棋之旅中(8.-11. 1998年4月)筛选了一些ARL晶体，然而，没有一个 它们被衍射到足够高的分辨率(优于8A) 数据收集。负责肉豆蔻酸化的酶 ARF和ARL的N-末端是N-肉豆蔻醇转移酶。这个 酵母中这种酶的结构已经确定，但 通过序列比较，与人类酶有足够的差异 我们正在确定人类酶的结构。这个 蛋白质结晶速度很慢，会产生非常小的晶体 衍射率不够好，无法进行内部数据收集。完成了85% HNMT的数据集(3A分辨率)是在CHESS(8.-11)中获得的。 1998年4月)，在低温条件下。我们正在使用 酵母NMT在分子置换尝试中与这些数据相协调。 到目前为止，我们已经获得了两个有希望的解决方案，它们必须是 在我们有一个明确的答案之前，进一步分析。

This project is focussed on the elucidation of structures of proteins in the secretory pathway. The key protein in vesicle formation is the ADP ribosylation factor that sequesters the proteins required for vesicle formation to the membrane. The protein behaves like an on/off switch where the GDP form is soluble in the cytosol and the GTP form is membrane associated. One of the elements that is essential for membrane association is a myristyl group at the N-terminus of the protein, without which membrane association does not occur. So far, the structure of the human ARF1 has been determined, and structures of yeast ARF1 and ARF2 are underway. In addition to the ARF's, cells also contain ARF-related proteins, called ARL's, that seem to have a function similar to that of ARF, but not identical. We have crystallized ARL1 from drosophila in hopes of obtaining a structure that might indicate what the differences between ARL and ARF are, and how they relate to cellular function. These crystals are too small for in-house data collection. During the trip to CHESS (8.-11. April 1998) a number of ARL crystals were screened, however, none of them diffracted to high enough resolution (better than 8A) for useful data collection. The enzyme responsible for myristylation at the N-terminus of the ARF's and ARL's is N-myristyl transferase. The structure of this enzyme from yeast has been determined, but is sufficiently different from the human enzyme by sequence comparison that we are determining the structure of the human enzyme. The protein crystallizes slowly and produces very small crystals that do not diffract well enough for in-house data collection. A 85% complete data set (to 3A resolution) of the hNMT was obtained at CHESS (8.-11. April 1998) under cryo conditions. We are in the process of using the yeast NMT coordinates to these data in molecular replacement attempts. So far, we have obtained two promising solutions that have to be analyzed further before we have a definitive answer.