Molecular characterization of caveolin association with the Golgi complex: identification of a cis-Golgi targeting domain in the caveolin molecule.
Caveolins are integral membrane proteins which are a major component of caveolae. In addition, caveolins have been proposed to cycle between intracellular compartments and the cell surface but the exact trafficking route and targeting information in the caveolin molecule have not been defined. We show that antibodies against the caveolin scaffolding domain or against the COOH terminus of caveolin-1 show a striking specificity for the Golgi pool of caveolin and do not recognize surface caveolin by immunofluorescence. To analyze the Golgi targeting of caveolin in more detail, caveolin mutants were expressed in fibroblasts. Specific mutants lacking the NH2 terminus were targeted to the cis Golgi but were not detectable in surface caveolae. Moreover, a 32-amino acid segment of the putative COOH-terminal cytoplasmic domain of caveolin-3 was targeted specifically and exclusively to the Golgi complex and could target a soluble heterologous protein, green fluorescent protein, to this compartment. Palmitoylation-deficient COOH-terminal mutants showed negligible association with the Golgi complex. This study defines unique Golgi targeting information in the caveolin molecule and identifies the cis Golgi complex as an intermediate compartment on the caveolin cycling pathway.
Luetterforst
R
R
Centre for Microscopy and Microanalysis, Department of Physiology and Pharmacology, and Centre for Molecular and Cellular Biology, University of Queensland, Brisbane, Queensland 4072, Australia.
Stang
E
E
Zorzi
N
N
Carozzi
A
A
Way
M
M
Parton
R G
RG
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D017124:Conserved Sequence / Q000235:genetics; D005347:Fibroblasts; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D015739:Nocodazole / Q000494:pharmacology; D019308:Palmitic Acid / Q000378:metabolism; D011485:Protein Binding; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000096:biosynthesis / Q000276:immunology; D017384:Sequence Deletion; D014162:Transfection
D000906:Antibodies; C495540:CAV1 protein, human; D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins; D008565:Membrane Proteins; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D019308:Palmitic Acid; D015739:Nocodazole