Characterization of the ros1-gene products expressed in human glioblastoma cell lines.

Most glioblastoma-derived cell lines express an 8.3 kb ros1 transcript and a 280 kD glycoprotein designated gp280ros1, which can be specifically immunoprecipitated with an anti-ROS antibody. This 280 kD protein possesses in vitro autokinase activity and was observed in four independent glioblastoma cell lines. In a fifth glioblastoma cell line, U-118 MG, a smaller ros1 transcript of 4.0 kb was observed. Immunoprecipitation analysis reveals that the U-118 MG expressed a smaller, 116 kD ros1 gene product. cDNA cloning and sequencing of the U-118 MG ros1 transcript indicates it encodes the entire tyrosine kinase domain and two amino acids of the transmembrane domain of ros1 at its 3' end. Sequences at its 5' end likely arise from another gene.