Cell Biology

Container Recycling

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Science  01 Oct 2004:
Vol. 306, Issue 5693, pp. 21-23
DOI: 10.1126/science.306.5693.21d

Caveolae — microscopic flask-shaped structures at the cell surface — can promote the internalization of a variety of ligands and viruses. What has not been clear is the extent to which cargo internalized via this route might mingle with cargo acquired by classical endocytosis.

Pelkmans et al. used live cell imaging to monitor caveolar structures and cargos, as well as early endosomal structures, and looked for where and when the internalized cargo was delivered to preexisting endosomal structures. The caveolin containers carried their cargo into the cell and docked with endosomes. Upon fusion with the endosome, the caveolin components did not disperse into bulk endosomal membrane; instead, they remained intact and eventually recycled en bloc back to the cell surface. On the other hand, exposure to the low endosomal pH did induce a cholera toxin cargo to diffuse out of the caveolar patches into the bulk endosomal membrane. The ability of caveolae to maintain structural integrity through a cycle of membrane internalization, fusion, and retrieval may be important in defining when and where cargos are delivered. — SMH

Cell 118, 767 (2004).

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