Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The p21 products of ras proto-oncogenes are GTP-binding proteins with associated GTPase activity. Recent studies have indicated that ras p21 may be required for the initiation of normal cell DNA synthesis, since microinjection of a monoclonal antibody, Y13-259, blocks serum stimulation of DNA synthesis in quiescent cell cultures (L. S. Mulcahy, M.R. Smith, and D. W. Stacey, Nature [London] 313:241-243, 1985). We localized the structural domain within the p21 molecule recognized by the Y13-259 monoclonal antibody. By analysis of a series of bacterially expressed p21 deletion mutants, the monoclonal antibody was found to interact with a region between positions 70 and 89 in the p21 amino acid sequence. By comparison of the coding sequences of different p21 proteins recognized by this monoclonal antibody, a highly conserved amino acid region between positions 70 and 81 was found to be the most likely site for the epitope detected by the Y13-259 antibody. This monoclonal antibody was further shown not to interfere directly with in vitro biochemical functions of the molecule, including GTP binding, GTPase, and autokinase activities.
Mol Cell Biol 1986 Apr
PMID:Monoclonal antibody Y13-259 recognizes an epitope of the p21 ras molecule not directly involved in the GTP-binding activity of the protein. 243 Dec 73

The neutralizing monoclonal antibody Y13-259 severely hampers the nucleotide exchange reaction between p21-bound and exogenous guanine nucleotides but does not interfere with the association of GDP to p21. These results suggest that the nucleotide exchange reaction is critical for p21 function. Interestingly, the v-ras p21 has a much faster dissociation rate than the p21 of the c-ras proto-oncogene.
Mol Cell Biol 1987 May
PMID:Neutralizing monoclonal antibody against ras oncogene product p21 which impairs guanine nucleotide exchange. 243 1

Prolonged alpha/beta interferon (IFN-alpha/beta) treatment of NIH 3T3 cells transformed by a long terminal repeat-activated Ha-ras proto-oncogene resulted in revertants that maintained a nontransformed phenotype long after IFN treatment had been discontinued. Cloned persistent revertants (PRs) produced large amounts of the ras-encoded p21 and were refractile to transformation by EJras DNA and by transforming retroviruses which carried the v-Ha-ras, v-Ki-ras, v-abl, or v-fes oncogene. Transient treatment either in vitro or in vivo with cytidine analogs that alter gene expression by inhibiting DNA methylation resulted in transformation of PR, but not of NIH 3T3, cells. The PR retransformants reverted again with IFN, suggesting that DNA methylation is involved in IFN-induced persistent reversion.
Mol Cell Biol 1987 Jun
PMID:Interferon-induced revertants of ras-transformed cells: resistance to transformation by specific oncogenes and retransformation by 5-azacytidine. 243 4

We have generated deletion mutants of the H-ras p21 protein which lack residues 58 to 63 or 64 to 68 and contain either the normal glycine or an activating mutation, arginine, at position 12. None of the deleted proteins were recognized by monoclonal antibody Y13-259, and those mutants with activating mutations showed at least a 100-fold reduction in their transforming activities compared with the activities of their nondeleted counterparts. Alterations observed in the in vitro GTPase or GTP interchange properties of the deletion mutants were not consistent with the decrease in their transforming activities. Moreover, each mutant showed normal membrane localization, which is essential for its biological activity. Recently, a newly identified protein, designated GTPase-activating protein (GAP), was found to markedly increase GTPase activity of the normal ras p21 but not of p21 mutants bearing activating lesions (H. Adari, D. R. Lowy, B. M. Willumsen, C. J. Der, and F. McCormick, Science 240:518-521, 1988). We showed that GAP had no effect on the in vitro GTPase activity of the deletion mutants of the normal p21 protein. Since similar deletions in mutants with activating lesions at position 12 or 59 or both showed decreased transforming activity, our results suggest that the recognition site for Y13-259 within the ras p21 molecule influences directly or indirectly the interaction of ras p21 with GAP and that this interaction is critical for biological activity of ras proteins.
Mol Cell Biol 1989 Apr
PMID:H-ras mutants lacking the epitope for the neutralizing monoclonal antibody Y13-259 show decreased biological activity and are deficient in GTPase-activating protein interaction. 247 Oct 68

We recently developed rat fibroblast cell lines that stably overproduce high levels of the beta 1 form of protein kinase C (PKC). These cells display several disorders in growth control and form small microscopic colonies in agar. In the present study we demonstrate that one of these cell lines, R6-PKC3, is extremely susceptible to transformation by an activated human bladder cancer c-H-ras oncogene (T24). Compared with control cell line R6-C1, T24-transfected R6-PKC3 cells yielded a 10-fold increase in the formation of large colonies in agar. Cell lines established from these colonies displayed a highly transformed morphology, expressed the T24-encoded p21 ras protein, continued to express high levels of PKC, and were highly tumorigenic in nude mice. These results provide genetic evidence that PKC mediates some of the effects of the c-H-ras oncogene on cell transformation. Data are also presented suggesting that optimum synergistic effects between c-H-ras and PKC require critical levels of their respective activities. These findings may be relevant to the process of multistage carcinogenesis in tissues containing cells with an activated c-H-ras oncogene.
Mol Cell Biol 1989 Jun
PMID:Cells that overproduce protein kinase C are more susceptible to transformation by an activated H-ras oncogene. 247 57

We have shown that the oncogenic EJ-ras gene, under the control of a metallothionein-I (Mt) promoter, can be induced to cause an increased susceptibility of transfected 10T1/2 fibroblasts to cytolysis mediated by natural killer (NK) cells. This effect may be specific to the ras gene family, since other oncogenes that we have tested here (src) and elsewhere (myc) do not show this effect. We have now examined the effect of modulating the level of p21 in both a positive or negative manner. The level of p21 ras was decreased by two independent mechanisms. First Zn2+ was removed from Mt-EJ-ras transformed cells. In the second approach we transfected 10T1/2 cells with a Mt-anti-sense c-H-ras construct which reduced p21 expression, slowed the growth rate and altered the morphology of 10T1/2 cells when induced with Zn. Surprisingly, the decrease in p21 ras levels by both approaches caused a marked increase in NK susceptibility (NKS) which was equivalent to that observed when the p21 ras levels were increased either by inducing EJ-ras or removing Zn2+ from Mt-anti-sense c-H-ras containing cells. The kinetics of induction of NK sensitivity due to decreasing normal p21 ras levels was identical to that observed for increasing mutated p21 ras levels. Peak enhancement of NKS was observed 24 hr after ras perturbation. These results suggest that either a positive or negative change in the steady-state level of p21 ras is sufficient to induce NK sensitivity, and NK sensitivity is not inextricably linked to cellular transformation by the ras gene.
Mol Immunol 1989 Oct
PMID:Decreased p21 levels in anti-sense ras transfectants augments NK sensitivity. 248 May 18

To investigate the function of activated oncogenes we attempted to create transgenic mice carrying activated human c-Ha-ras genes which have their own promoters. However, we never obtained any transgenic pups which developed to term, because all transgenic embryos were malformed, became developmentally arrested conceptuses or developed embryonic tumors during ontogenesis. The mRNA expression of the transgenes was detected in two tumors obtained after introduction of the DNA fragment containing the activated human c-Ha-ras gene for p21 with valine at the 12th codon or with leucine at the 61st codon. Histological analysis indicated that each tumor consisted of at least three types of cells: two originating from different germ layers (the endoderm in one case and the mesoderm in the other) and the third from extra embryonic ectoderm. It was suggested that the activated human c-Ha-ras gene has a critical effect on the development of tumors in normal embryos as well as in transformation of NIH3T3 cells.
Mol Biol Med 1989 Dec
PMID:Embryonal tumors from transgenic mouse zygotes carrying human activated c-Ha-ras genes. 248 36

The rho genes constitute an evolutionarily conserved family having significant homology to the ras oncogene family. These genes have been found in Saccharomyces cerevisiae, Drosophila melanogaster, rat, and human; their 21,000-dalton products show strong conservation of structure. In humans, three classes of rho cDNA clones have been identified which differ by virtue of the presence of variable C-terminal domains: rhoH12, rhoH6, and rhoH9. The predicted 193 amino acids of human rhoH12 protein show 88% similarity with those of the human rhoH6 clone, 96.8% similarity with those of the Aplysia rho product, and 81.8% similarity with those of the yeast RHO1 protein. Rat-1 and NIH 3T3 mouse fibroblasts were transfected with clones containing the normal human rhoH12 allele as well as the variants encoding valine in place of the glycine and leucine in place of the glutamine normally found at residues 14 and 64, respectively. These replacements mirror the changes responsible for oncogenic activation of the related ras-encoded p21 proteins. These mutant rhoH12 clone alleles did not cause focus formation in monolayers or growth in soft agar. However, amplification of normal rhoH12 via cotransfection with a dihydrofolate reductase gene resulted in colonies that displayed reduced dependence on serum for growth, grew to higher saturation densities, and were tumorigenic when inoculated into nude mice. Normal p21rho protein was detected in the transfected cell lines as well as in normal cell lines by Western immunoblot and immunoprecipitation analysis with rabbit antibodies raised against the peptide corresponding to amino acids 122 to 135.
Mol Cell Biol 1989 May
PMID:Characterization and expression of the human rhoH12 gene product. 250 57

We have purified to near homogeneity and characterized three small molecular weight (Mr) GTP-binding proteins, the c-Ki-ras protein (c-Ki-ras p21), the rho protein (rho p20) and a novel smg-25A protein (smg p25A), from bovine brain crude membranes. In the present studies, the intrasynaptosomal distribution of these 3 small Mr G protein has been investigated using bovine brain. ras p21 and rho p20 are found in the synaptosomal membrane fraction but not in the synaptosomal soluble fraction. In contrast, smg p25A is found in both the synaptosomal membrane and soluble fractions. These results indicate that the intrasynaptosomal distribution of these small Mr G proteins is different and suggest that they are involved in different neuronal functions.
Brain Res Mol Brain Res 1989 Nov
PMID:Intrasynaptosomal distribution of the ras, rho and smg-25A GTP-binding proteins in bovine brain. 251 9

Residues 32 to 40, which are conserved among ras proteins from different species, are likely to participate in interactions with the p21 effector system. With the goal of understanding the structural basis of the regulatory functions of c-Ha-ras p21, we produced rabbit antisera against a synthetic peptide corresponding to amino acids 33 to 42 of the protein. The affinity-purified antibodies interacted specifically with p21 and with the antigenic peptide. The epitope recognized by the antibodies appeared to be centered on threonine 35. The antibodies inhibited both in vitro p21-induced production of cyclic AMP in detergent extracts of RAS-defective yeast membranes and GAP-stimulated GTPase activity. However, monoclonal anti-ras antibodies Y13-259 and Y13-238 were not capable of specifically inhibiting interactions of p21 with these two putative effector proteins. The apparent inhibitory effect of Y13-259 on stimulation of p21 by GAP was due to a greatly reduced rate of exchange of nucleotides in the binding pocket of the protein. These findings provide additional support for the essential role of the residue 32 to 40 domain as the true effector site and further evidence of the involvement of GAP as a cellular effector of ras proteins.
Mol Cell Biol 1989 Sep
PMID:Antibodies to synthetic peptide from the residue 33 to 42 domain of c-Ha-ras p21 block reconstitution of the protein with different effectors. 255 Aug 7


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