Multiple forms of 22 kDa caveolin-1 alpha present in bovine lens cells could reflect variable palmitoylation.
Two-dimensional immunoblots of immunoprecipitated caveolin-1 from cultured bovine lens epithelial cells revealed four to five-22 kDa forms of caveolin-1 alpha with isoelectric points of between pH values 5.5 and 6.6. Fibre cell membrane recovered from fresh bovine lenses displayed an even greater number of multiforms, some with isoelectric point pH values as low as about 4. Caveolin-1 can be both phosphorylated and palmitoylated. None of the caveolin-1 alpha multiforms were labelled following culture of the lens epithelial cells with 32P-orthophosphate nor were they recognized by either caveolin-specific phosphotyrosine antibody or protein anti-phosphoserine antibody and treatment of lens fibre cell membrane with phosphatase did not alter the two-dimensional profile of immunoreactive caveolins. However, short-term incubation of BLEC with 3H-palmitate labelled some of the immunoprecipitated caveolin-1 multiforms. We suggest that the observed spectrum of caveolin multiforms could reflect variable palmitoylation of its three cysteine residues and result in populations of caveolin-1 alpha molecules with separate physical and functional properties.
Cenedella
Richard J
RJ
Department of Biochemistry, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, MO 63501, USA.
Neely
Amanda R
AR
Sexton
Patricia
P
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002417:Cattle; D051242:Caveolin 1 / Q000032:analysis* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D047468:Immunoprecipitation; D007526:Isoelectric Point; D007553:Isotope Labeling; D007908:Lens, Crystalline / Q000166:cytology* / Q000378:metabolism; D010168:Palmitates / Q000378:metabolism; D020033:Protein Isoforms / Q000032:analysis
D051242:Caveolin 1; D010168:Palmitates; D020033:Protein Isoforms