title: Genetic analysis of the Kirsten-ras-revertant 1 gene: potentiation of its tumor suppressor activity by specific point mutations.
abstract: Kirsten-ras-revertant 1 (Krev-1) cDNA encodes a ras-related protein and exhibits an activity of inducing flat revertants at certain frequencies (2-5% of total transfectants) when introduced into a v-K-ras-transformed mouse NIH 3T3 cell line, DT. Toward understanding the mechanism of action of Krev-1 protein, we constructed a series of point mutants of Krev-1 cDNA and tested their biological activities in DT cells and HT1080 human fibrosarcoma cells harboring the activated N-ras gene. Substitutions of the amino acid residues in the putative guanine nucleotide-binding regions (Asp17 and Asn116), in the putative effector-binding domain (residue 38), at the putative acylation site (Cys181), and at the unique Thr61 all decreased the transformation suppressor activity. On the other hand, substitutions such as Gly12 to Val12 and Gln63 to Glu63 were found to significantly increase the transformation suppressor/tumor suppressor activity of Krev-1. These findings are consistent with the idea that Krev-1 protein is regulated like many other G proteins by the guanine triphosphate/guanine diphosphate-exchange mechanism probably in response to certain negative growth-regulatory signals.
authors.affiliation: Laboratory of Molecular Oncology, Tsukuba Life Science Center, Ibaraki, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kitayama
authors.forename: T
authors.initials: T
authors.lastname: Matsuzaki
authors.forename: Y
authors.initials: Y
authors.lastname: Ikawa
authors.forename: M
authors.initials: M
authors.lastname: Noda
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D004252:DNA Mutational Analysis; D019204:GTP-Binding Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009374:Neoplasms, Experimental / Q000473:pathology*; D009841:Oligonucleotides; D015689:Oncogene Protein p21(ras) / Q000235:genetics*; D009857:Oncogenes; D013329:Structure-Activity Relationship; D013489:Suppression, Genetic; D014162:Transfection; D020668:rap GTP-Binding Proteins
chemical_list: D009841:Oligonucleotides; D019204:GTP-Binding Proteins; D015689:Oncogene Protein p21(ras); D020668:rap GTP-Binding Proteins