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

该项目的重点是阐明的结构， 分泌途径中的蛋白质。 囊泡中的关键蛋白 形成的ADP核糖基化因子， 所需的囊泡形成的膜。 蛋白质的行为 就像一个开关，其中GDP形式可溶于胞质溶胶， GTP形式是膜结合的。 其中一个要素是 膜结合所必需的是在膜结合位点的肉豆蔻基。 蛋白质的N-末端，没有它，膜结合就不能 发生. 到目前为止，人类ARF 1的结构已经确定， 酵母ARF 1和ARF 2的结构正在进行中。 除了 ARF细胞也含有ARF相关蛋白，称为ARL， 似乎具有与ARF相似的功能，但不完全相同。 我们 从果蝇中结晶出ARL 1， 可能表明ARL和ARF之间差异的结构 以及它们与细胞功能的关系。 这些水晶也 对于内部数据收集来说很小。 在国际象棋之旅（8. 11. 1998年4月）筛选了一些ARL晶体，然而， 它们衍射到足够高的分辨率（优于8A）， 数据收集。 负责肉豆蔻酰化的酶在 ARF和ARL的N-末端是N-肉豆蔻基转移酶。 的 已经确定了来自酵母的这种酶的结构，但是 通过序列比较与人类酶充分不同 我们正在确定人体酶的结构。 的 蛋白质结晶缓慢，产生非常小的晶体， 不足以进行内部数据收集。 完成了85% hNMT的数据集（至3A分辨率）是在CHESS（8. 11. 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协调。 到目前为止，我们已经得到了两个有希望的解决方案， 在我们得到明确的答案之前，我们需要进一步分析。

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.