title: Oligomerization of VIP21-caveolin in vitro is stabilized by long chain fatty acylation or cholesterol.
abstract: VIP21-caveolin is one of the components which form the cytoplasmic surface of caveolae. In vivo, this integral membrane protein is found in homo-oligomers with molecular masses of approximately 200, 400 and 600 kDa. These oligomers are also formed by the addition of cytosol to the in vitro synthesized and membrane inserted VIP21-caveolin. Here we show that long chain fatty acyl coenzyme A esters can completely substitute for cytosol in inducing 200 kDa and 400 kDa complexes, whereas 25-hydroxy-cholesterol can produce the 200 kDa oligomer. In order to understand whether acylation of VIP21-caveolin itself is a prerequisite for oligomerization, we studied a mutant protein lacking all three cysteines. When analyzed by velocity sucrose gradient centrifugation in the presence of the non-ionic detergent octylglucoside, both palmitoylated and non-palmitoylated VIP21-caveolin formed oligomers that were indistinguishable. However, only the oligomers of the non-palmitoylated protein are disrupted when analyzed by SDS-PAGE without boiling. These data suggest that the protein domains of VIP21-caveolin are the primary determinants of oligomerization, but that palmitoylation of cysteine residues can increase the stability of the oligomers.
authors.affiliation: Department of Cell Biology, Max-Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Monier
authors.forename: D J
authors.initials: DJ
authors.lastname: Dietzen
authors.forename: W R
authors.initials: WR
authors.lastname: Hastings
authors.forename: D M
authors.initials: DM
authors.lastname: Lublin
authors.forename: T V
authors.initials: TV
authors.lastname: Kurzchalia
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism*; D000215:Acylation; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins; D002460:Cell Line; D003545:Cysteine / Q000378:metabolism; D004285:Dogs; D006801:Humans; D006888:Hydroxycholesterols / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism
chemical_list: D000214:Acyl Coenzyme A; C495540:CAV1 protein, human; D002352:Carrier Proteins; D051242:Caveolin 1; D022461:Caveolins; D006888:Hydroxycholesterols; D008565:Membrane Proteins; D010169:Palmitic Acids; D019308:Palmitic Acid; C007997:25-hydroxycholesterol; D003545:Cysteine