Increased pp60c-src tyrosyl kinase activity in human neuroblastomas is associated with amino-terminal tyrosine phosphorylation of the src gene product.
We have observed a 20- to 40-fold increase in pp60c-src tyrosyl kinase activity in human neuroblastoma cell lines over that found in either human glioblastoma cells or human fibroblasts. The level of c-src gene transcripts and pp60c-src protein synthesis in the neuroblastoma cells was not significantly increased when compared to the levels found in glioblastoma cells. Approximately one-half of the pp60c-src molecules synthesized during a 4-hr [35S]methionine or [32P]orthophosphate labeling period in neuroblastoma cells were found to migrate more slowly on NaDodSO4/polyacrylamide gels than pp60c-src molecules labeled in glioblastoma cells. Peptide and phosphoamino acid analysis of the in vivo phosphorylated c-src molecules from these two cell types revealed that pp60c-src molecules from the neuroblastoma cells possess in the amino-terminal portion of the protein at least one unique tyrosine phosphorylation site not found in pp60c-src derived from glioblastoma cells.
J B
JB
Bolen
N
N
Rosen
M A
MA
Israel
D002460:Cell Line; D005347:Fibroblasts / Q000201:enzymology; D005910:Glioma / Q000201:enzymology; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism*; D009447:Neuroblastoma / Q000201:enzymology*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src); D014158:Transcription, Genetic; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src)