酵母出芽是一种高度极性化的细胞生长，研究其调控机制具有重要科学意义。Boi1和Boi2是酿酒酵母中一对含有SH3、SAM和PH等结构域的同源蛋白质，它们定位于细胞表面的极性生长位点，在芽体的极性生长过程中发挥着重要的调控功能，然而，Boi蛋白的定位与功能机制却不太清楚。本项目计划以Boi2为研究对象，鉴定其分子内介导定位与调控极性生长的功能结构域，随后，筛选鉴定能够与Boi2的功能域相互作用并对Boi2的定位与功能发挥起着重要作用的蛋白质，以揭示Boi2定位与调控极性生长的机制，待鉴定的候选分子包括Cdc42模块成员、前期工作中鉴定得到的相互作用蛋白Rho3、Yol019w、Dse1和Msb1等。此外，还将解析Boi2的磷酸化以及Boi2与14-3-3家族成员Bmh1之间的相互作用对其活性的影响，以揭示Boi2的活性在胞内如何受到调控。本项目对于阐明酵母细胞极性生长的调控机制具有重要意义。

Yeast budding is one type of highly polarized cell growth. It is scientifically important to explore its regulatory mechanism. Boi1 and Boi2 are a pair of paralogous proteins bearing SH3, SAM and PH domains in Saccharomyces cerevisiae. They are localized to the sites of polarized growth on the cell surface and play critical roles in the control of polarized cell growth. However, the mechanism by which the two Boi proteins localize to the polarity sites and control polarized growth is not well understood. In this proposal, we choose Boi2 as a representative of Boi proteins. We plan to delineate the functional domains in Boi2 that mediate Boi2’s localization to the polarity sites as well as Boi2’s function in the control of polarized growth. Subsequently, we plan to look for proteins that interact with Boi2’s functional domain and play important role in Boi2’s localization and function, aiming to elucidate the mechanisms by which Boi2 localizes and controls polarized growth. The protein candidates include several components of the Cdc42 module, Boi2 interactors identified previously in our lab including Rho3, Yol019w, Dse1 and Msb1. In addition, we plan to investigate the regulation of Boi2 activity by phosphorylation and the interaction of Boi2 with Bmh1, a member of the phosphopeptide-binding 14-3-3 family, aiming to reveal how Boi2 activity is regulated in the cells. Our proposed investigation will provide new insight in the understanding of regulation on polarized cell growth in yeast.