Endosome Acidification and the Pathways of Receptor-Mediated Endocytosis
Receptor-mediated endocytosis serves a variety of physiologically significant purposes (Goldstein et al., 1985). These include regulation of surface receptors, clearance of various macromolecules from the circulation, uptake of nutrients, transport of macromolecules across cells, cholesterol homeostasis, infection by some viruses, and penetration into the cytoplasm by certain toxins. Many basic steps in the endocytic pathways have been elucidated, but some of the essential features of this process remain poorly understood. Several organelles have been identified as being involved in endocytic events. However, in many cases the characteristics and function of these organelles are uncertain. Few proteins have been identified which are highly enriched in the individual endocytic compartments, and virtually nothing is known of the molecular recognition signals which govern targeting of proteins to specific endocytic or membrane recycling compartments.
KeywordsWild Type Cell Chinese Hamster Ovary Cell Lysosomal Enzyme Diphtheria Toxin Endocytic Pathway
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