Brief Communication abstract
Nature Cell Biology 4, 374 - 378 (2002)
Published online: 15 April 2002 | doi:10.1038/ncb787
There is an Addendum (June 2002) associated with this Brief Communication.
A distinct class of endosome mediates clathrin-independent endocytosis to the Golgi complex
Benjamin J. Nichols1
Mammalian cells endocytose a variety of proteins and lipids without utilising clathrin-coated pits1, 2, 3, 4, 5. Detailed molecular mechanisms for clathrin-independent endocytosis are unclear. Several markers for this process, including glycosphingolipid-binding bacterial toxin subunits such as cholera toxin B subunit (CTxB), and glycosyl-phosphatidyl-inositol (GPI)-anchored proteins, are found in detergent-resistant membrane fractions (DRMs), or 'lipid rafts'2, 3, 5, 6, 7. The Golgi complex constitutes one principal intracellular destination for these markers2. Uptake of both CTxB and GPI-anchored proteins may involve caveolae, small invaginations in the plasma membrane (PM)8, 9, 10, 11, 12, 13. However, the identity of intermediate organelles involved in PM to Golgi trafficking, as well as the function of caveolins, defining protein components of caveolae12, 13, are unclear. This paper shows that molecules which partition into DRMs and are endocytosed in a clathrin-independent fashion, accumulate in a discrete population of endosomes en route to the Golgi complex. These endosomes are devoid of markers for classical early and recycling endosomes, but do contain caveolin-1. Caveolin-1-positive endosomes are sites for the sorting of caveolin-1 away from Golgi-bound cargoes, although caveolin-1 itself is unlikely to have a direct function in PM to Golgi transport.
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
Correspondence to: Benjamin J. Nichols1 e-mail: ben@mrc-lmb.cam.ac.uk
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