PIF3 PHOSPHORYLATION SITES AND ASSOCIATED PROTEINS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 光敏色素（phy）家族的感觉光感受器控制植物对来自环境的光信号的适应性反应。目前的数据表明，信号转导过程涉及光激活的光感受器分子从细胞质到细胞核的快速易位，在那里它与bHLH转录因子家族的一部分成员（称为光敏色素相互作用因子（PIFs））发生物理相互作用，诱导靶基因的转录反应。最近的证据表明，PIF家族的成员在黑暗中抑制发育，并且光活化的phy通过在暴露于光时诱导PIF分子的快速降解来逆转这种抑制。该过程涉及相互作用的bHLH蛋白的快速的、phy诱导的磷酸化，随后通过泛素蛋白酶体系统降解。该项目的这一部分的具体，主要重点是确定PIF 3分子中的光诱导磷酸化位点，作为理解磷酸化机制及其在标记bHLH因子泛素化中所起作用的一步。第二个相关的目标是鉴定由光诱导与PIF 3蛋白相互作用的蛋白质，作为鉴定负责信号传导过程中磷酸化和泛素化步骤的蛋白激酶和E3连接酶的一个步骤。 建议使用质谱分析来解决这两个目标。

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. The phytochrome (phy) family of sensory photoreceptors control plant adaptational responses to light signals from the environment. Current data indicate that the signal transduction process involves rapid translocation of the light-activated photoreceptor molecule from the cytoplasm to the nucleus, where it interacts physically with a subset of members of the bHLH transcription-factor family, termed phytochrome-interacting factors (PIFs), inducing transcriptional responses in target genes. Recent evidence shows that members of the PIF family repress development in the dark, and that photoactivated phy reverses this repression by inducing rapid degradation of the PIF molecules upon exposure to light. This process involves rapid, phy-induced phosphorylation of the interacting bHLH protein, followed by degradation via the ubiquitin proteasome system. The specific, primary focus of this segment of the project is to identify the light-induced phosphorylation sites in the PIF3 molecule, as a step toward understanding the mechanism of phosphorylation and the role it plays in tagging the bHLH factor for ubiquitylation. A second related objective is to identify proteins that are induced by light to interact with the PIF3 protein as a step toward identifying the protein kinase and E3 ligase responsible for the phosphorylation and ubiquitylation steps in the signaling process. It is proposed to use mass spec analysis to address both these objectives.