A molecular dissection of caveolin-1 membrane attachment and oligomerization. Two separate regions of the caveolin-1 C-terminal domain mediate membrane binding and oligomer/oligomer interactions in vivo.
Caveolins form interlocking networks on the cytoplasmic face of caveolae. The cytoplasmically directed N and C termini of caveolins are separated by a central hydrophobic segment, which is believed to form a hairpin within the membrane. Here, we report that the caveolin scaffolding domain (CSD, residues 82-101), and the C terminus (residues 135-178) of caveolin-1 are each sufficient to anchor green fluorescent protein (GFP) to membranes in vivo. We also show that the first 16 residues of the C terminus (i.e. residues 135-150) are necessary and sufficient to attach GFP to membranes. When fused to the caveolin-1 C terminus, GFP co-localizes with two trans-Golgi markers and is excluded from caveolae. In contrast, the CSD targets GFP to caveolae, albeit less efficiently than full-length caveolin-1. Thus, caveolin-1 contains at least two membrane attachment signals: the CSD, dictating caveolar localization, and the C terminus, driving trans-Golgi localization. Additionally, we find that caveolin-1 oligomer/oligomer interactions require the distal third of the caveolin-1 C terminus. Thus, the caveolin-1 C-terminal domain has two separate functions: (i) membrane attachment (proximal third) and (ii) protein/protein interactions (distal third).
Schlegel
A
A
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Lisanti
M P
MP
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3; D022461:Caveolins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
C495540:CAV1 protein, human; C495541:Cav1 protein, mouse; C495537:Cav1 protein, rat; C495548:Cav3 protein, mouse; C495549:Cav3 protein, rat; D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3; D022461:Caveolins; D008164:Luminescent Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins