Some protein tyrosine phosphatases target in part to lipid rafts and interact with caveolin-1.
A profile-based search of the SWISS-PROT database reveals that most protein tyrosine phosphatases (PTPs) contain at least one caveolin-1-binding motif. To ascertain if the presence of caveolin-binding motif(s) in PTPs corresponds to their actual localization in caveolin-1-enriched membrane fractions, we performed subcellular fractionating experiments. We found that all tested PTPs (PTP1B, PTP1C, SHPTP2, PTEN, and LAR) are actually localized in caveolin-enriched membrane fractions, despite their distribution in other subcellular sites, too. More than 1/2 of LAR and about 1/4 of SHPTP2 and PTP-1C are localized in caveolin-enriched membrane fractions whereas, in these fractions, PTP-1B and PTEN are poorly concentrated. Co-immunoprecipitation experiments with antibodies specific for each tested PTP demonstrated that all five phosphatases form molecular complexes with caveolin-1 in vivo. Collectively, our findings propose that particular PTPs could perform some of their cellular actions or are regulated by recruitment into caveolin-enriched membrane fractions.
Caselli
A
A
Department of Biochemical Sciences, University of Florence, Viale Morgagni 50, 50134 Florence, Italy.
Mazzinghi
B
B
Camici
G
G
Manao
G
G
Ramponi
G
G
D020816:Amino Acid Motifs; D001665:Binding Sites; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D046911:Macromolecular Substances; D021962:Membrane Microdomains / Q000201:enzymology* / Q000378:metabolism; D011233:Precipitin Tests; D021381:Protein Transport; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*
C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D046911:Macromolecular Substances; D017027:Protein Tyrosine Phosphatases