Caveolin-1 and a 29-kDa caveolin-associated protein are phosphorylated on tyrosine in cells expressing a temperature-sensitive v-Abl kinase

Caveolin-1 was originally identified as a tyrosine-phosphorylated protein i n v-Src-transformed cells and it was suggested that phosphorylation of this protein could mediate transformation by the tyrosine kinase class of oncog enes (J. R. Glenney, 1989, J. Biol. Chem. 264, 20163-20166). We found that caveolin-1 is also phosphorylated on tyrosine in v-Abl-transformed cells. I n fact, caveolin-1 and a caveolin-associated protein of 29 kDa are among th e strongest phosphotyrosine signals detected in the Abl-expressing cells. I n addition, v-Abl shows a preferential phosphorylation of caveolin-1 and th e 29-kDa caveolin-associated protein over other proteins in the caveolin-en riched Triton-resistant cell fraction. These data indicate that caveolin-1 and the 29-kDa caveolin-associated protein may be preferred substrates of t he Abl kinase. Caveolin-1 is phosphorylated at tyrosine 14 in v-Abl-express ing cells as has been observed previously in v-Src-expressing cells. Howeve r, using a temperature-sensitive allele of v-Abl (ts120 v-Abl) we provide e vidence that caveolin-1 phosphorylation is not sufficient to mediate the lo ss of caveolin expression or loss of cell adhesion induced by v-Abl. (C) 20 01 Academic Press.