Molecular cloning and characterization of p56dok-2 defines a new family of RasGAP-binding proteins.
Chronic myelogenous leukemia (CML) is a disease characterized by the presence of p210(bcr-abl), a chimeric protein with tyrosine kinase activity. Substrates for p210(bcr-abl) are likely to be involved in the pathogenesis of CML. Here we describe the purification, cDNA cloning, and characterization of a 56-kDa tyrosine phosphorylated protein, p56(dok-2) (Dok-2), from p210(bcr-abl) expressing cells. The human dok-2 cDNA encodes a 412-amino acid protein with a predicted N-terminal pleckstrin homology domain as well as several other features of a signaling molecule, including 13 potential tyrosine phosphorylation sites, six PXXP motifs, and the ability to bind to p120(RasGAP). Dok-2 was shown to be 35% identical to p62(dok-1), a recently identified RasGAP binding protein from CML cells, and analysis of the expressed sequence tag data base revealed the presence of at least four additional proteins containing a Dok homology sequence motif. Dok mRNAs were primarily expressed in tissues of hematopoietic origin. These findings strongly suggest that a family of Dok-related proteins exists that bind to RasGAP and may mediate the effects of p210(bcr-abl) in CML.
Pubmed ID: 9478921 RIS Download
Adaptor Proteins, Signal Transducing | Amino Acid Sequence | Animals | Carrier Proteins | Cell Line | Cloning, Molecular | DNA, Complementary | DNA-Binding Proteins | Fusion Proteins, bcr-abl | GTPase-Activating Proteins | Hematopoietic Stem Cells | Humans | Leukemia, Myelogenous, Chronic, BCR-ABL Positive | Mice | Molecular Sequence Data | Phosphoproteins | Phosphorylation | Protein Binding | Protein-Tyrosine Kinases | Proteins | RNA-Binding Proteins | Sequence Homology, Amino Acid | Signal Transduction | Tissue Distribution