Visualizing the endocytic and exocytic processes of wheat germ agglutinin by quantum dot-based single-particle tracking

Wheat germ agglutinin (WGA) is a paradigm for understanding intracellular transport of lectins. As a protein exploiting the receptor-mediated endocytosis for internalization, WGA is also a valuable model system for exploring the endocytic and exocytic pathway. In this study, quantum dot-based single-particle tracking was performed to investigate the transport of WGA in live cells, revealing firstly that the endocytic and exocytic processes of WGA were both actin- and microtubule-dependent, each including five stages. The vesicle fusion event occurred near the cytomembrane, followed by two destinies with WGA: shedding to the extracellular or reversing to the cytoplasm. These findings suggest a distinct and dynamic scenario for the transport of lectins following a receptor-mediated endo/exocytic pathway in live cells. This is important for the application of lectins as drug carriers and antineoplastic drugs in medicine, and also offers insights into the pathway of endocytosis and exocytosis.