Despite their significance in receptor-mediated internalization and continued signal transduction in cells, early/sorting endosomes (EE/SE) remain incompletely characterized, with many outstanding questions that surround the dynamics of their size and number. While several studies have reported increases in EE/SE size and number resulting from endocytic events, few studies have addressed such dynamics in a methodological and quantitative manner. Herein we apply quantitative fluorescence microscopy to measure the size and number of EE/SE upon internalization of two different ligands: transferrin and epidermal growth factor. Additionally, we used siRNA knock-down to determine the involvement of 5 different endosomal RAB proteins (RAB4, RAB5, RAB8A, RAB10 and RAB11A) in EE/SE dynamics. Our study provides new information on the dynamics of endosomes during endocytosis, an important reference for researchers studying receptor-mediated internalization and endocytic events.

尽管早期/分选内体（EE/SE）在细胞内受体介导的内化和持续信号转导中具有重要意义，但其特征仍然不完全，围绕其大小和数量的动态存在许多悬而未决的问题。虽然一些研究报告了内吞事件导致 EE/SE 大小和数量的增加，但很少有研究以方法和定量的方式解决这种动态。在此，我们应用定量荧光显微镜来测量两种不同配体（转铁蛋白和表皮生长因子）内化后 EE/SE 的大小和数量。此外，我们使用 siRNA 敲除来确定 5 种不同的内体 RAB 蛋白（RAB4、RAB5、RAB8A、RAB10 和 RAB11A）在 EE/SE 动力学中的参与情况。我们的研究提供了内吞过程中内体动力学的新信息，为研究受体介导的内化和内吞事件的研究人员提供了重要参考。