Mechanism of caveolin filament assembly.
Caveolin-1 was the first protein identified that colocalizes with the approximately 10-nm filaments found on the inside surface of caveolae membranes. We have used a combination of electron microscopy (EM), circular dichroism, and analytical ultracentrifugation to determine the structure of the oligomers that form when the first 101 aa of caveolin-1 (Cav(1-101)) are allowed to associate. We determined that amino acids 79-96 in this caveolin-1 fragment are arranged in an alpha-helix. Cav(1-101) oligomers are approximately 11 nm in diameter and contain seven molecules of Cav(1-101). These subunits, in turn, are able to assemble into 50 nm long x 11 nm diameter filaments that closely match the morphology of the filaments in the caveolae filamentous coat. We propose that the heptameric subunit forms in part through lateral interactions between the alpha-helices of the seven Cav(1-101) units. Caveolin-1, therefore, appears to be the structural molecule of the caveolae filamentous coat.
Fernandez
Imma
I
Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75235-9039, USA.
Ying
Yunshu
Y
Albanesi
Joseph
J
Anderson
Richard G W
RG
D021941:Caveolae / Q000648:ultrastructure; D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3; D022461:Caveolins / Q000737:chemistry*; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003001:Cloning, Molecular; D005613:Freeze Etching; D008854:Microscopy, Electron; D008958:Models, Molecular; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D020033:Protein Isoforms / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D014461:Ultracentrifugation
D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3; D022461:Caveolins; D020033:Protein Isoforms; D011994:Recombinant Proteins