CRYSTALLOGRAPHIC STUDIES OF THE AQP0-CAM COMPLEX

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。 我们研究了水通道蛋白0(AQP0)，这是一种来自眼睛晶状体的跨膜水通道，当突变时会导致晶状体严重损伤、白内障和失明。AQP0通过与钙调蛋白相互作用，对[Ca~(2+)]的变化作出反应，从而调节眼晶状体内的水分渗透性。钙调素(CaM)是一种普遍存在的胞浆蛋白，常与钙离子调节偶联。我们认为，钙/钙调素与AQP0的相互作用导致水通道内的主要构象变化，从而影响水的通透性。这项建议的目的是利用X射线结晶学来确定AQP0-CaM络合物的高分辨率结构。我们可以疲倦地生长同时含有AQP0和CaM的大晶体，但由于衍射率低，高分辨率结构信息的获得一直受到阻碍。成功地实现我们的目标将在水通道调控领域产生广泛的影响，同时也将对钙/钙调素信号系统和膜结构生物学的进一步发展产生更广泛的影响。

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. We study aquaporin 0 (AQP0), a transmembrane water channel from the eye lens, causing severe lesions in the lens, cataracts and blindness when mutated. AQP0 regulates water permeability within the eye lens by responding to changes in [Ca2+] through an interaction with calmodulin. Calmodulin (CaM) is a ubiquitous cytosolic protein commonly coupled with Ca2+ regulation. We suggest the Ca2+/CaM interaction with AQP0 lead to major conformational changes within the water channels that enfluence water permeability rates. The aims of this proposal are to use X-ray crystallography to determine the high-resolution structure of the AQP0-CaM complex. We can fatihfully grow large crystals containing both AQP0 and CaM, however obtaining high-resolution structural information has been stymied by poor diffraction. Success in achieving our aim will have wide implications in the fields of water channel regulation, as well as broader implications to the Ca2+/CaM signaling system and to furthering membrane structural biology in general.