Crkl is the major tyrosine-phosphorylated protein in neutrophils from patients with chronic myelogenous leukemia.
The Philadelphia chromosome (Ph1), detected in virtually all cases of chronic myelogenous leukemia (CML), is formed by a reciprocal translocation between chromosome 9 and 22 that fuses Bcr-encoded sequences upstream of exon 2 of c-Abl. This oncogene produces a fusion protein, p210bcr-abl, in which the Abl tyrosine kinase activity is elevated. Using anti-phosphotyrosine immunoblotting, we have compared the pattern of phosphotyrosine-containing proteins from freshly prepared neutrophils of patients in the stable phase of CML to normal controls. The only consistent difference was the presence of a 39-kDa tyrosine-phosphorylated protein in 18 out of 18 neutrophil samples from CML patients that was not seen in normal controls. This same protein, as assessed by two-dimensional anti-phosphotyrosine immunoblotting, was also present in cell lines expressing p210bcr-abl, including K562 cells. Using K562 cells as a source of protein, the 39-kDa protein was purified and identified by microsequencing as Crkl, an SH2/SH3 adaptor protein related to the crk oncogene of the avian sarcoma virus, CT10. A direct interaction between Crkl and Abl has also been shown using a yeast two-hybrid screen.
Oda
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Division of Hematology and Medical Oncology, Oregon Health Sciences University, Portland 97201.
Heaney
C
C
Hagopian
J R
JR
Okuda
K
K
Griffin
J D
JD
Druker
B J
BJ
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D017931:DNA Primers; D015180:Electrophoresis, Gel, Two-Dimensional; D016044:Fusion Proteins, bcr-abl / Q000097:blood; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000097:blood* / Q000302:isolation & purification; D009504:Neutrophils / Q000378:metabolism*; D009687:Nuclear Proteins / Q000097:blood* / Q000302:isolation & purification; D010766:Phosphorylation; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000097:blood*
D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D017931:DNA Primers; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D014443:Tyrosine; D016044:Fusion Proteins, bcr-abl