A RING finger motif regulates transforming activity of the rfp/ret fusion gene.
The rfp/ret transforming gene was generated by DNA rearrangement which occurred during transfection of NIH 3T3 cells. The amino-terminal half of Rfp with a RING finger motif was fused to the truncated Ret receptor tyrosine kinase, leading to a transforming sequence, Rfp/Ret. In the present study, to elucidate the importance of a RING finger motif for its transforming activity, we mutated cysteine or histidine residues present in the motif that are believed to be crucial for the tertiary structure of the protein. Substitution of Cys-16, Cys-31, or His-33 markedly decreased the transforming activity of Rfp/Ret. These mutations also resulted in a striking decrease of tyrosine phosphorylation of the mutant proteins in transfectants. In contrast, mutations of Cys-118 or His-124 in the second cysteine/histidine-rich motif (called B box) of Rfp/Ret did not affect its activity. These results thus indicated that the RING finger structure is critical for the full transforming activity of Rfp/Ret.
Hasegawa
N
N
Department of Pathology, Nagoya University School of Medicine, Japan.
Iwashita
T
T
Asai
N
N
Murakami
H
H
Iwata
Y
Y
Isomura
T
T
Goto
H
H
Hayakawa
T
T
Takahashi
M
M
D016475:3T3 Cells; D000818:Animals; D002461:Cell Line, Transformed; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D051379:Mice; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D000070584:Tripartite Motif Proteins
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D044767:Ubiquitin-Protein Ligases; C489296:Trim27 protein, mouse; D000070584:Tripartite Motif Proteins; C416649:Ret protein, Drosophila; C494999:Ret protein, mouse