Cholesterol transporter caveolin‐1 transits the lipid bilayer during intracellular cycling

Caveolin‐1, a major protein of cell surface invaginations called caveolae, is currently believed to cycle between the plasma membrane and intracellular compartments via the endocytotic pathway, at least for part of its itinerary. We studied the distribution of caveolin‐1 in cell membranes, using ult...

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Bibliographic Details
Published in:The FASEB journal 2003-10, Vol.17 (13), p.1-14
Main Authors: Robenek, Mirko J., Schlattmann, Karin, Zimmer, Klaus-Peter, Plenz, Gabriele, Troyer, David, Robenek, Horst
Format: Article
Language:English
Subjects:
Animals
Caveolin 1
Caveolins - analysis
Caveolins - metabolism
Cell Membrane - chemistry
Cell Membrane - ultrastructure
Cholesterol - metabolism
endocytotic pathway
Intracellular Membranes - chemistry
Intracellular Membranes - ultrastructure
intracellular transport
Lipid Bilayers - metabolism
lipid droplets
membrane leaflet
Membrane Transport Proteins - analysis
Membrane Transport Proteins - metabolism
Models, Biological
Protein Transport
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Summary:Caveolin‐1, a major protein of cell surface invaginations called caveolae, is currently believed to cycle between the plasma membrane and intracellular compartments via the endocytotic pathway, at least for part of its itinerary. We studied the distribution of caveolin‐1 in cell membranes, using ultrathin cryosections and freeze‐fracture immunolabeling and found this protein not only in the cytoplasmic leaflet of the plasma membrane, but also in the exoplasmic leaflet of all intracellular membranes. This sidedness implies that caveolin‐1 switches from one membrane leaflet to the other somewhere on its way through the cell and rules out the classic mechanism of endocytotic membrane budding and fusion for caveolin‐1 intracellular trafficking. Underlying the sidedness of caveolin‐1 may be a fundamental, hitherto unrecognized, mechanism by which proteins transit membranes.
ISSN:0892-6638
1530-6860
DOI:10.1096/fj.03-0008fje