School of Life Sciences, The University of Nottingham, Nottingham, UK.
School of Computer Science, Nottingham Trent University, Nottingham, UK.
J Biol Chem. 2023 May;299(5):104703. doi: 10.1016/j.jbc.2023.104703. Epub 2023 Apr 12.
The conversion of signal transducer and activator of transcription (STAT) proteins from latent to active transcription factors is central to cytokine signaling. Triggered by their signal-induced tyrosine phosphorylation, it is the assembly of a range of cytokine-specific STAT homo- and heterodimers that marks a key step in the transition of hitherto latent proteins to transcription activators. In contrast, the constitutive self-assembly of latent STATs and how it relates to the functioning of activated STATs is understood less well. To provide a more complete picture, we developed a co-localization-based assay and tested all 28 possible combinations of the seven unphosphorylated STAT (U-STAT) proteins in living cells. We identified five U-STAT homodimers-STAT1, STAT3, STAT4, STAT5A, and STAT5B-and two heterodimers-STAT1:STAT2 and STAT5A:STAT5B-and performed semi-quantitative assessments of the forces and characterizations of binding interfaces that support them. One STAT protein-STAT6-was found to be monomeric. This comprehensive analysis of latent STAT self-assembly lays bare considerable structural and functional diversity in the ways that link STAT dimerization before and after activation.
信号转导子和转录激活子(STAT)蛋白从潜伏状态到活性转录因子的转化是细胞因子信号转导的核心。在信号诱导的酪氨酸磷酸化作用下,一系列细胞因子特异性 STAT 同源和异源二聚体的组装标志着从先前潜伏状态的蛋白质向转录激活剂的转变的关键步骤。相比之下,潜伏 STAT 的组成型自组装及其与激活 STAT 的功能关系理解得较少。为了提供更完整的画面,我们开发了一种基于共定位的测定法,并在活细胞中测试了七个未磷酸化 STAT(U-STAT)蛋白的所有 28 种可能组合。我们鉴定了五个 U-STAT 同源二聚体-STAT1、STAT3、STAT4、STAT5A 和 STAT5B-和两个异源二聚体-STAT1:STAT2 和 STAT5A:STAT5B-并对半定量评估了支持它们的结合界面的力和特性。一个 STAT 蛋白-STAT6-被发现是单体。这种对潜伏 STAT 自组装的全面分析揭示了在激活前后的 STAT 二聚化中存在相当大的结构和功能多样性。