Reconstructing the Evolution of the Endocytic System: Insights from Genomics and Molecular Cell Biology
Endocytosis is an essential process undertaken by most eukaryotic cells. At its most general, the term refers to the uptake of material from the cell milieu.1 Cell biologists, however, have come to recognise a number of distinct modes of endocytic transport that are accompanied by differences in their underlying molecular mechanisms. Multiple modes can coexist in the same cell type and are frequendy ongoing concurrendy. Broadly, endocytic mechanisms can be subdivided based on the size of the ingested particle or cargo. Phagocytosis, or cell eating, is the uptake of large particles, including whole cells, and is accompanied by transport through large vesicular structures (>250nm in diameter). Pinocytosis, or cell drinking, involves uptake of rather smaller cargo, typically macromolecules and complexes. The study of endocytic pathways has, for very good technical reasons, focused on a small number of taxa, principally metazoa, yeast and a restricted number of protists. This has served well and has allowed the definition of a number of pathways in part by virtue of the molecules that are required for their operation.
KeywordsNuclear Pore Complex Endocytic Pathway Secondary Loss Thalassiosira Pseudonana Last Common Eukaryotic Ancestor
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