Among the FGF proteins, the least characterized superfamily is the group of fibroblast growth factor homologous factors (FHFs). To date, the main role of FHFs has been primarily seen in the modulation of voltage-gated ion channels, but a full picture of the function of FHFs inside the cell is far from complete. In the present study, we focused on identifying novel FGF12 binding partners to indicate its intracellular functions. Among the identified proteins, a significant number were nuclear proteins, especially RNA-binding proteins involved in translational processes, such as ribosomal processing and modification. We have demonstrated that FGF12 is localized to the nucleolus, where it interacts with NOLC1 and TCOF1, proteins involved in the assembly of functional ribosomes. Interactions with both NOLC1 and TCOF1 are unique to FGF12, as other FHF proteins only bind to TCOF1. The formation of nucleolar FGF12 complexes with NOLC1 and TCOF1 is phosphorylation-dependent and requires the C-terminal region of FGF12. Surprisingly, NOLC1 and TCOF1 are unable to interact with each other in the absence of FGF12. Taken together, our data link FHF proteins to nucleoli for the first time and suggest a novel and unexpected role for FGF12 in ribosome biogenesis.

中文翻译：

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FGF12 是核仁 NOLC1/TCOF1 核糖体生物发生复合物的新成分

在 FGF 蛋白中，特征最少的超家族是成纤维细胞生长因子同源因子 (FHF) 组。迄今为止，FHF 的主要作用主要体现在电压门控离子通道的调制中，但细胞内 FHF 功能的全貌还远未完成。在本研究中，我们专注于鉴定新的 FGF12 结合伙伴以表明其细胞内功能。在已鉴定的蛋白质中，大量是核蛋白，尤其是参与翻译过程的 RNA 结合蛋白，例如核糖体加工和修饰。我们已经证明 FGF12 定位于核仁，在那里它与参与功能性核糖体组装的蛋白质 NOLC1 和 TCOF1 相互作用。与 NOLC1 和 TCOF1 的相互作用是 FGF12 独有的，因为其他 FHF 蛋白仅与 TCOF1 结合。核仁 FGF12 与 NOLC1 和 TCOF1 复合物的形成是磷酸化依赖性的，需要 FGF12 的 C 末端区域。令人惊讶的是，在没有 FGF12 的情况下，NOLC1 和 TCOF1 无法相互作用。综上所述，我们的数据首次将 FHF 蛋白与核仁联系起来，并表明 FGF12 在核糖体生物发生中具有新的意想不到的作用。