title: An alteration of the human c-abl protein in K562 leukemia cells unmasks associated tyrosine kinase activity.
abstract: The v-abl protein is known to be a tyrosine-specific protein kinase. However, its normal cellular homolog, c-abl P150, is not detectably phosphorylated on tyrosine in vivo or in vitro. The lack of associated tyrosine kinase activity for the c-abl protein seems paradoxical since it is the c-abl-derived sequences of the v-abl protein that encode the kinase activity. We have detected an altered human c-abl protein (P210) with associated tyrosine kinase activity in the K562 leukemia cell line. K562 cells are known to have a 9:22 chromosomal translocation involving the c-abl locus and have amplified the c-able gene 4 to 8 fold. The altered P210 human c-abl is serologically and structurally related to the normal c-abl protein. A structural alteration of the human c-abl protein. K562 cells may have unmasked its associated tyrosine kinase activity. This altered c-abl protein may have important implications for a mechanism of activation of this oncogene.
mesh_terms: D000818:Animals; D002472:Cell Transformation, Viral; D004273:DNA, Neoplasm / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D007942:Leukemia, Experimental / Q000201:enzymology / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics; D009857:Oncogenes; D010446:Peptide Fragments / Q000032:analysis; D010750:Phosphoproteins / Q000502:physiology; D019000:Phosphotyrosine; D011494:Protein Kinases / Q000235:genetics*; D011505:Protein-Tyrosine Kinases; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases