The complex ultrastructure of the endolysosomal system.
Live-cell imaging reveals the endolysosomal system as a complex and highly dynamic network of interacting compartments. Distinct types of endosomes are discerned by kinetic, molecular, and morphological criteria. Although none of these criteria, or combinations thereof, can capture the full complexity of the endolysosomal system, they are extremely useful for experimental purposes. Some membrane domain specializations and specific morphological characteristics can only be seen by ultrastructural analysis after preparation for electron microscopy (EM). Immuno-EM allows a further discrimination of seemingly identical compartments by their molecular makeup. In this review we provide an overview of the ultrastructural characteristics and membrane organization of endosomal compartments, along with their organizing machineries.
Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
Judith
J
Klumperman
Institut Curie, Centre de Recherche, Paris F-75248, France Structure and Membrane Compartments CNRS UMR144, Paris F-75248, France.
Graça
G
Raposo
D022163:Clathrin-Coated Vesicles / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000502:physiology; D011992:Endosomes / Q000502:physiology* / Q000648:ultrastructure; D056945:Hep G2 Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D008954:Models, Biological