title: CRKL links p210BCR/ABL with paxillin in chronic myelogenous leukemia cells.
abstract: The Philadelphia chromosome translocation generates a chimeric oncogene, BCR/ABL, which causes chronic myelogenous leukemia (CML). In primary neutrophils from patients with CML, the major novel tyrosine-phosphorylated protein is CRKL, an SH2-SH3-SH3 linker protein which has an overall homology of 60% to CRK, the human homologue of the v-crk oncogene product. Anti-CRKL immunoprecipitates from CML cells, but not normal cells, were found to contain p210BCR/ABL and c-ABL. Several other phosphoproteins were also detected in anti-CRKL immunoprecipitates, one of which has been identified as paxillin, a 68-kDa focal adhesion protein which we have previously shown to be phosphorylated by p210BCR/ABL. Using GST-CRKL fusion proteins, the SH3 domains of CRKL were found to bind c-ABL and p210BCR/ABL, while the SH2 domain of CRKL bound to paxillin, suggesting that CRKL could physically link p210BCR/ABL to paxillin. Paxillin contains three tyrosines in Tyr-X-X-Pro (Y-X-X-P) motifs consistent with amino acid sequences predicted to be optimal for binding to the CRKL-SH2 domain (at positions Tyr-31, Tyr-118, and Tyr-181). Each of these tyrosine residues was mutated to a phenylalanine residue, and in vitro binding assays indicated that paxillin tyrosines at positions 31 and 118, but not 181, are likely to be involved in CRKL-SH2 binding. These results suggest that the p210BCR/ABL oncogene may be physically linked to the focal adhesion-associated protein paxillin in hematopoietic cells by CRKL. This interaction could contribute to the known adhesive defects of CML cells.
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001665:Binding Sites; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism*; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D003598:Cytoskeletal Proteins; D009687:Nuclear Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D014443:Tyrosine; D016044:Fusion Proteins, bcr-abl