Protein Engineering, Lilly Biotechnology Center, Eli Lilly and Company, San Diego, CA 92121, USA.
Int J Mol Sci. 2020 Jul 2;21(13):4719. doi: 10.3390/ijms21134719.
The cell membrane is a complex and highly regulated system that is composed of lipid bilayer and proteins. One of the main functions of the cell membrane is the regulation of cell entry. Cell-penetrating peptides (CPPs) are defined as peptides that can cross the plasma membrane and deliver their cargo inside the cell. The uptake of a peptide is determined by its sequence and biophysicochemical properties. At the same time, the uptake mechanism and efficiency are shown to be dependent on local peptide concentration, cell membrane lipid composition, characteristics of the cargo, and experimental methodology, suggesting that a highly efficient CPP in one system might not be as productive in another. To better understand the dependence of CPPs on the experimental system, we present a review of the in vitro assays that have been employed in the literature to evaluate CPPs and CPP-cargos. Our comprehensive review suggests that utilization of orthogonal assays will be more effective for deciphering the true ability of CPPs to translocate through the membrane and enter the cell cytoplasm.
细胞膜是一个复杂且高度调节的系统，由脂质双层和蛋白质组成。细胞膜的主要功能之一是调节细胞进入。细胞穿透肽（CPPs）被定义为能够穿过质膜并将其货物递送到细胞内的肽。肽的摄取取决于其序列和生物物理化学性质。同时，摄取机制和效率被证明取决于局部肽浓度、细胞膜脂质组成、货物特性和实验方法学，这表明在一个系统中高效的 CPP 在另一个系统中可能效果不佳。为了更好地理解 CPP 对实验系统的依赖性，我们回顾了文献中用于评估 CPP 和 CPP-货物的体外测定法。我们的全面综述表明，使用正交测定法将更有效地破译 CPP 穿过膜并进入细胞质的真实能力。
