2Department of Medical Physics, St. Petersburg State Polytechnical University, St. Petersburg, Russia; fax: +7 (812) 297-3169; E-mail: email@example.com
Received April 29, 2014
Receptor-mediated endocytosis is the most specific pathway for macromolecules and macromolecular complexes generally designated as ligands to enter cells. Upon binding to their transmembrane receptors, the ligands enter endocytic vesicles that fuse with each other giving rise to the so-called early endosomes. The sorting of ligand–receptor complexes internalized in these endosomes depends on their nature: metabolic receptors are recycled back to the plasma membrane, while signaling receptors and their ligands (e.g. receptor tyrosine kinases or receptors associated with tyrosine kinase) are delivered to internal vesicles of the multivesicular late endosomes and finally are degraded after interaction with lysosomes. During these processes, endosomes undergo translocation from the cell periphery to the juxtanuclear region, which is accompanied by multiple fusion, invagination, tabulation, and membrane fission events. This review considers modern concepts of the sorting mechanisms of ligand–receptor complexes, the crosstalk between endosomes, microtubules, and actin, and the role of this crosstalk in endosome maturation.
KEY WORDS: endosomes, ligand–receptor complexes, sorting complexes, microtubules, microfilaments, domain organization of endosomes, membrane remodeling