Protein–membrane interactions play key roles in essential cellular processes; studying these interactions in the cell is a challenging task of modern biophysical chemistry. A prominent example is the interaction of human α-synuclein (αS) with negatively charged membranes. It has been well-studied in vitro, but in spite of the huge amount of lipid membranes in the crowded environment of biological cells, to date, no interactions have been detected in cells. Here, we use rapid-scan (RS) electron paramagnetic resonance (EPR) spectroscopy to study αS interactions with negatively charged vesicles in vitro and upon transfection of the protein and lipid vesicles into model cells, i.e., oocytes of Xenopus laevis. We show that protein–vesicle interactions are reflected in RS spectra in vitro and in cells, which enables time-resolved monitoring of protein–membrane interaction upon transfection into cells. Our data suggest binding of a small fraction of αS to endogenous membranes.

中文翻译：

---

快速扫描电子顺磁共振波谱研究的细胞内蛋白质-脂质相互作用

蛋白质-膜相互作用在基本细胞过程中起关键作用。研究细胞中的这些相互作用是现代生物物理化学的一项艰巨任务。一个突出的例子是人α-突触核蛋白（αS）与带负电荷的膜的相互作用。在体外已经对其进行了充分研究，但是尽管在拥挤的生物细胞环境中存在大量脂质膜，但迄今为止，在细胞中未检测到相互作用。在这里，我们使用快速扫描（RS）电子顺磁共振（EPR）光谱来研究αS与带负电荷的囊泡在体外以及蛋白质和脂质囊泡转染到模型细胞（即非洲爪蟾的卵母细胞）中的相互作用。。我们证明了蛋白质-囊泡的相互作用在体外和细胞中都反映在RS光谱中，这使得在转染到细胞后能够对蛋白质-膜的相互作用进行时间分辨的监测。我们的数据表明一小部分αS与内源膜结合。