scholarly journals p21 ras proteins and guanine nucleotides modulate the phosphorylation of 36- and 17-kilodalton mitochondria-associated proteins.

1986 ◽  
Vol 83 (17) ◽  
pp. 6357-6361 ◽  
Author(s):  
J. M. Backer ◽  
I. B. Weinstein
Keyword(s):  
Guanine Nucleotides ◽  
Ras Proteins ◽  
P21 Ras ◽  
Associated Proteins

scholarly journals Fetal hyperinsulinemia increases farnesylation of p21 Ras in fetal tissues

2001 ◽  
Vol 281 (2) ◽  
pp. E217-E223 ◽  
Author(s):  
Elizabeth Stephens ◽  
Patti J. Thureen ◽  
Marc L. Goalstone ◽  
Marianne S. Anderson ◽  
J. Wayne Leitner ◽  
...  
Keyword(s):  
Growth Factors ◽  
Molecular Mechanisms ◽  
Fetal Liver ◽  
White Blood Cells ◽  
Causative Factor ◽  
Ras Proteins ◽  
Direct Infusion ◽  
Fetal Tissues ◽  
P21 Ras

Even though the role of fetal hyperinsulinemia in the pathogenesis of fetal macrosomia in patients with overt diabetes and gestational diabetes mellitus seems plausible, the molecular mechanisms of action of hyperinsulinemia remain largely enigmatic. Recent indications that hyperinsulinemia “primes” various tissues to the mitogenic influence of growth factors by increasing the pool of prenylated Ras proteins prompted us to investigate the effect of fetal hyperinsulinemia on the activitiy of farnesyltransferase (FTase) and the amounts of farnesylated p21 Ras in fetal tissues in the ovine experimental model. Induction of fetal hyperinsulinemia by direct infusion of insulin into the fetus and by either fetal or maternal infusions of glucose resulted in significant increases in the activity of FTase and the amounts of farnesylated p21 Ras in fetal liver, skeletal muscle, fat, and white blood cells. An additional infusion of somatostatin into hyperglycemic fetuses blocked fetal hyperinsulinemia and completely prevented these increases, specifying insulin as the causative factor. We conclude that the ability of fetal hyperinsulinemia to increase the size of the pool of farnesylated p21 Ras may prime fetal tissues to the action of other growth factors and thereby constitute one mechanism by which fetal hyperinsulinemia could induce macrosomia in diabetic pregnancies.

scholarly journals Biochemical characterization of polypeptides encoded by mutated human Ha-ras1 genes.

1986 ◽  
Vol 6 (2) ◽  
pp. 730-734 ◽  
Author(s):  
W W Colby ◽  
J S Hayflick ◽  
S G Clark ◽  
A D Levinson
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Kinase Activity ◽  
Biochemical Characterization ◽  
Strong Support ◽  
Guanine Nucleotides ◽  
Amino Acid Substitutions ◽  
Gtpase Activity ◽  
P21 Ras

We expressed six forms of p21-ras polypeptides in Escherichia coli with differing transformation potentials resulting from amino acid substitutions at position 12. The ability of the encoded p21's to autophosphorylate, bind guanine nucleotides, and hydrolyze GTP was assessed. All versions of p21 bound GTP equivalently; the kinase activity, while dependent upon residue 12, did not correlate with the transforming potential of the polypeptide. All transforming versions exhibited an impaired GTPase activity, while a novel nontransforming derivative [p21(pro-12)] possessed an enhanced GTPase activity. These results provide strong support for the proposal that an impairment of the cellular p21 GTPase activity can unmask its transforming potential.

scholarly journals Influence of guanine nucleotides on complex formation between Ras and CDC25 proteins.

1993 ◽  
Vol 13 (3) ◽  
pp. 1345-1352 ◽  
Author(s):  
C C Lai ◽  
M Boguski ◽  
D Broek ◽  
S Powers
Keyword(s):  
Fusion Protein ◽  
Guanine Nucleotides ◽  
Free Form ◽  
Physical Interaction ◽  
Nucleotide Exchange ◽  
Ras Proteins ◽  
Positive Role ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors

The Saccharomyces cerevisiae CDC25 gene and closely homologous genes in other eukaryotes encode guanine nucleotide exchange factors for Ras proteins. We have determined the minimal region of the budding yeast CDC25 gene capable of activity in vivo. The region required for full biological activity is approximately 450 residues and contains two segments homologous to other proteins: one found in both Ras-specific exchange factors and the more distant Bud5 and Lte1 proteins, and a smaller segment of 48 amino acids found only in the Ras-specific exchange factors. When expressed in Escherichia coli as a fusion protein, this region of CDC25 was found to be a potent catalyst of GDP-GTP exchange on yeast Ras2 as well as human p21H-ras but inactive in promoting exchange on the Ras-related proteins Ypt1 and Rsr1. The CDC25 fusion protein catalyzed replacement of GDP-bound to Ras2 with GTP (activation) more efficiently than that of the reverse reaction of replacement of GTP for GDP (deactivation), consistent with prior genetic analysis of CDC25 which indicated a positive role in the activation of Ras. To more directly study the physical interaction of CDC25 and Ras proteins, we developed a protein-protein binding assay. We determined that CDC25 binds tightly to Ras2 protein only in the absence of guanine nucleotides. This higher affinity of CDC25 for the nucleotide-free form than for either the GDP- or GTP-bound form suggests that CDC25 catalyzes exchange of guanine nucleotides bound to Ras proteins by stabilization of the transitory nucleotide-free state.

Biochemical characterization of polypeptides encoded by mutated human Ha-ras1 genes

1986 ◽  
Vol 6 (2) ◽  
pp. 730-734
Author(s):  
W W Colby ◽  
J S Hayflick ◽  
S G Clark ◽  
A D Levinson
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Kinase Activity ◽  
Biochemical Characterization ◽  
Strong Support ◽  
Guanine Nucleotides ◽  
Amino Acid Substitutions ◽  
Gtpase Activity ◽  
P21 Ras

We expressed six forms of p21-ras polypeptides in Escherichia coli with differing transformation potentials resulting from amino acid substitutions at position 12. The ability of the encoded p21's to autophosphorylate, bind guanine nucleotides, and hydrolyze GTP was assessed. All versions of p21 bound GTP equivalently; the kinase activity, while dependent upon residue 12, did not correlate with the transforming potential of the polypeptide. All transforming versions exhibited an impaired GTPase activity, while a novel nontransforming derivative [p21(pro-12)] possessed an enhanced GTPase activity. These results provide strong support for the proposal that an impairment of the cellular p21 GTPase activity can unmask its transforming potential.

scholarly journals Glucagon and p21 ras enhance the phosphorylation of the same 38-kilodalton membrane protein from rat liver cells.

1990 ◽  
Vol 10 (6) ◽  
pp. 2468-2474 ◽  
Author(s):  
A N Hegde ◽  
M R Das
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
G Proteins ◽  
Rat Liver ◽  
Guanine Nucleotide ◽  
Ras Proteins ◽  
P21 Ras ◽  
Rat Liver Cells ◽  
Stimulation Of

We had reported earlier the enhanced phosphorylation of a 38-kilodalton protein (p38) in rat liver plasma membrane by ras proteins. Now we show that glucagon increased the phosphorylation of the same protein. The nature and site(s) of phosphorylation were the same as those for the ras proteins. Both ATP and GTP could donate phosphate for the phosphorylation of p38. The stimulation of p38 phosphorylation by glucagon was guanine nucleotide dependent. This observation, together with our data on the stimulation of p38 phosphorylation by AIF4-, suggest the involvement of G proteins in the reaction. We also showed that glucagon stimulates the phosphorylation of p38 in vivo.

scholarly journals Oligomeric structure of p21 ras proteins as determined by radiation inactivation.

1988 ◽  
Vol 263 (20) ◽  
pp. 9853-9858
Author(s):  
E Santos ◽  
A R Nebreda ◽  
T Bryan ◽  
E S Kempner
Keyword(s):  
Ras Proteins ◽  
Oligomeric Structure ◽  
Radiation Inactivation ◽  
P21 Ras

scholarly journals Insulin induction of Xenopus laevis oocyte maturation is inhibited by monoclonal antibody against p21 ras proteins.

1987 ◽  
Vol 7 (3) ◽  
pp. 1285-1288 ◽  
Author(s):  
A K Deshpande ◽  
H F Kung
Keyword(s):  
Monoclonal Antibody ◽  
Xenopus Laevis ◽  
Oocyte Maturation ◽  
Neutralizing Antibody ◽  
Xenopus Laevis Oocytes ◽  
Xenopus Laevis Oocyte ◽  
Ras Proteins ◽  
Ras Protein ◽  
P21 Ras

Microinjection of transforming p21 ras protein induces maturation of Xenopus laevis oocytes, and the induction is blocked by coinjection of monoclonal antibody (Y13-259) against p21 ras proteins. Similar to other inducing agents, the effect of p21 ras protein is mediated via the appearance of maturation or meiosis-promoting factor activity. In addition, the neutralizing antibody markedly reduces oocyte maturation after insulin induction, whereas it fails to inhibit progesterone induction. Our results suggest that insulin induces maturation of oocytes via a different pathway than that of steroidal agents. The induction by insulin is ras dependent, and the action of ras may be directed at the steps before meiosis-promoting factor autocatalytic activation. These results suggest a role of p21 ras protein in the events associated with amphibian oocyte maturation.

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