Inorganic polyphosphate (polyP) is an often-overlooked biopolymer of phosphate residues present in living cells. PolyP is associated with many essential biological roles. Despite interest in polyP’s function, most studies have been limited to extracellular or isolated protein experiments, as polyanionic polyP does not traverse the nonpolar membrane of cells. To address this problem, we developed a robust, readily employed method for polyP delivery using guanidinium-rich oligocarbonate transporters that electrostatically complex polyPs of multiple lengths, forming discrete nanoparticles that are resistant to phosphatase degradation and that readily enter multiple cell types. Fluorescently labeled polyPs have been monitored over time for subcellular localization and release from the transporter, with control over release rates achieved by modulating the transporter identity and the charge ratio of the electrostatic complexes. This general approach to polyP delivery enables the study of intracellular polyP signaling in a variety of applications.

中文翻译：

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使用两亲性低聚碳酸酯转运蛋白将无机多磷酸盐输送到细胞中

无机多磷酸盐 (polyP) 是活细胞中存在的一种经常被忽视的磷酸盐残基生物聚合物。PolyP 与许多重要的生物学作用相关。尽管对polyP的功能感兴趣，但大多数研究仅限于细胞外或分离的蛋白质实验，因为聚阴离子polyP不能穿过细胞的非极性膜。为了解决这个问题，我们开发了一种强大的、易于使用的聚P递送方法，使用富含胍的寡碳酸酯转运蛋白，静电复合多种长度的聚P，形成耐磷酸酶降解且易于进入多种细胞类型的离散纳米粒子。随着时间的推移，荧光标记的多聚蛋白的亚细胞定位和转运蛋白的释放已得到监测，通过调节转运蛋白的特性和静电复合物的电荷比来控制释放速率。这种多聚蛋白递送的通用方法使得能够在各种应用中研究细胞内多聚蛋白信号传导。