scholarly journals Guanine nucleotide activation of, and competition between, RAS proteins from Saccharomyces cerevisiae.

1987 ◽  
Vol 7 (6) ◽  
pp. 2128-2133 ◽  
Author(s):  
J Field ◽  
D Broek ◽  
T Kataoka ◽  
M Wigler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Active Form ◽  
Guanine Nucleotides ◽  
Guanine Nucleotide ◽  
Ras Proteins ◽  
Yeast Saccharomyces Cerevisiae ◽  
Inactive Form

In the yeast Saccharomyces cerevisiae, yeast RAS proteins are potent activators of adenylate cyclase. In the present work we measured the activity of adenylate cyclase in membranes from Saccharomyces cerevisiae which overexpress this enzyme. The response of the enzyme to added RAS2 proteins bound with various guanine nucleotides and their analogs suggests that RAS2 proteins are active in their GTP-bound form and are virtually inactive in their GDP-bound form. Also, active RAS2 protein is not inhibited by inactive RAS2, suggesting that the inactive form does not compete with the active form in binding to its effector.

scholarly journals Guanine nucleotide activation of, and competition between, RAS proteins from Saccharomyces cerevisiae

1987 ◽  
Vol 7 (6) ◽  
pp. 2128-2133
Author(s):  
J Field ◽  
D Broek ◽  
T Kataoka ◽  
M Wigler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Active Form ◽  
Guanine Nucleotides ◽  
Guanine Nucleotide ◽  
Ras Proteins ◽  
Yeast Saccharomyces Cerevisiae ◽  
Inactive Form

In the yeast Saccharomyces cerevisiae, yeast RAS proteins are potent activators of adenylate cyclase. In the present work we measured the activity of adenylate cyclase in membranes from Saccharomyces cerevisiae which overexpress this enzyme. The response of the enzyme to added RAS2 proteins bound with various guanine nucleotides and their analogs suggests that RAS2 proteins are active in their GTP-bound form and are virtually inactive in their GDP-bound form. Also, active RAS2 protein is not inhibited by inactive RAS2, suggesting that the inactive form does not compete with the active form in binding to its effector.

A new RAS mutation that suppresses the CDC25 gene requirement for growth of Saccharomyces cerevisiae

1988 ◽  
Vol 8 (7) ◽  
pp. 2980-2983
Author(s):  
J H Camonis ◽  
M Jacquet
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Gene Product ◽  
Guanine Nucleotides ◽  
Ras Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Ras Mutation ◽  
Exchange Factor ◽  
Ras Genes ◽  
Extragenic Suppressors

In the yeast Saccharomyces cerevisiae, the activation of adenylate cyclase requires the products of the RAS genes and of CDC25. We isolated several dominant extragenic suppressors of the yeast cdc25 mutation. They did not suppress a thermosensitive allele of the adenylate cyclase gene (CDC35). One of these suppressors was a mutated RAS2 gene in which the transition C/G----T/A at position 455 resulted in replacement of threonine 152 by isoleucine in the protein. The same mutation in a v-Ha-ras gene reduces the affinity of p21 for guanine nucleotides (L.A. Feig, B. Pan, T.M. Roberts, and G.M. Cooper, Proc. Natl. Acad. Sci. USA 83:4607-4611, 1986). These results support a model in which the CDC25 gene product is the GDP-GTP exchange factor regulating the activity of the RAS gene product.

scholarly journals A new RAS mutation that suppresses the CDC25 gene requirement for growth of Saccharomyces cerevisiae.

1988 ◽  
Vol 8 (7) ◽  
pp. 2980-2983 ◽  
Author(s):  
J H Camonis ◽  
M Jacquet
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Gene Product ◽  
Guanine Nucleotides ◽  
Ras Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Ras Mutation ◽  
Exchange Factor ◽  
Ras Genes ◽  
Extragenic Suppressors

In the yeast Saccharomyces cerevisiae, the activation of adenylate cyclase requires the products of the RAS genes and of CDC25. We isolated several dominant extragenic suppressors of the yeast cdc25 mutation. They did not suppress a thermosensitive allele of the adenylate cyclase gene (CDC35). One of these suppressors was a mutated RAS2 gene in which the transition C/G----T/A at position 455 resulted in replacement of threonine 152 by isoleucine in the protein. The same mutation in a v-Ha-ras gene reduces the affinity of p21 for guanine nucleotides (L.A. Feig, B. Pan, T.M. Roberts, and G.M. Cooper, Proc. Natl. Acad. Sci. USA 83:4607-4611, 1986). These results support a model in which the CDC25 gene product is the GDP-GTP exchange factor regulating the activity of the RAS gene product.

Properties and Possible Functions of the Adenylate Cyclase in Plasma Membranes of Saccharomyces cerevisiae

1982 ◽  
Vol 2 (12) ◽  
pp. 1481-1491
Author(s):  
Patrick K. Jaynes ◽  
James P. McDonough ◽  
Henry R. Mahler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Dissociation Constants ◽  
Guanine Nucleotides ◽  
Adenylate Cyclase System ◽  
Regulatory Subunits ◽  
Molecular Weights ◽  
Essential Components

We have examined the possible role of adenosine 3′,5′-phosphate (cAMP) in functions associated with the plasma membranes of Saccharomyces cerevisiae. Purified membranes from this source contained an adenylate cyclase which was insensitive to activation by fluoride or guanine nucleotides, only weakly responsive to changes of carbon source in the growth medium, and strongly stimulated by vanadate. They also contained at least two classes of receptor proteins for guanine nucleotides (as measured by binding of labeled 5′-guanylyl methylene diphosphate) with apparent dissociation constants equal to 1.0 × 10 −7 and 3 × 10 −6 M, a protein kinase capable of phosphorylating added histones, the activity of which was stimulated by cAMP, and cAMP receptors that may function as regulatory subunits for this kinase. Membrane proteins were also susceptible to phosphorylation by endogenous kinase(s), with polypeptides of apparent molecular weights equal to 160 × 10 3 , 135 × 10 3 , 114 × 10 3 , and 58 × 10 3 as the major targets. Of these, the 114,000-molecular-weight polypeptide was probably identical to the proton-translocating ATPase of the membranes. However, the cAMP-dependent protein kinase did not appear to be involved in these reactions. Intact ( rho + or rho 0 ) cells responded to dissipation of the proton electrochemical gradient across their plasma membranes by rapid and transient changes in their intracellular level of cAMP, as suggested earlier (J. M. Trevillyan and M. L. Pall, J. Bacteriol., 138 :397-403, 1979). Thus, although yeast plasma membranes contain all the essential components of a stimulus-responsive adenylate cyclase system, the precise nature of the coupling device and the targets involved remain to be established.

Forskolin stimulation of adenylate cyclase in human thyroid membranes

1985 ◽  
Vol 108 (2) ◽  
pp. 200-205 ◽  
Author(s):  
Kikuo Kasai ◽  
Yoshinobu Suzuki ◽  
Masaki Hiraiwa ◽  
Hisamoto Kuroda ◽  
Tatsushi Emoto ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Nucleotide Binding ◽  
Guanine Nucleotides ◽  
Human Thyroid ◽  
Guanine Nucleotide ◽  
Guanine Nucleotide Binding ◽  
Stimulation Of

Abstract. Forskolin stimulates adenylate cyclase in human thyroid membranes approximately 7-fold with halfmaximal stimulation occurring at 5–10 μm. Guanine nucleotides are not required for stimulation of the enzyme by forskolin. Forskolin-stimulation is additive or greater than additive with that of TSH or Gpp(NH)p-(above 1 μm). Different from TSH- or Gpp(NH)p-stimulation of adenylate cyclase, uncoupling of the guanine nucleotide-binding regulatory component by increasing concentrations of MnCl2 did not result in uncoupling of forskolin stimulation. The finding indicates that forskolin may mainly act on the catalytic component of adenylate cyclase. From the present study, it is suggested that the diterpene forskolin stimulates adenylate cyclase in human thyroid membranes by a novel mechanism that differs from TSH- or Gpp(NH)p-stimulation, and that the diterpene may be a useful tool to investigate the metabolism of thyroid and its regulation in normal and pathological situations.

scholarly journals Changes in gene expression in the Ras/adenylate cyclase system of Saccharomyces cerevisiae: correlation with cAMP levels and growth arrest.

1993 ◽  
Vol 4 (7) ◽  
pp. 757-765 ◽  
Author(s):  
M Russell ◽  
J Bradshaw-Rouse ◽  
D Markwardt ◽  
W Heideman
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Oxidative Metabolism ◽  
Growth Arrest ◽  
Intracellular Camp ◽  
Adenylate Cyclase System ◽  
Diauxic Shift ◽  
Yeast Saccharomyces Cerevisiae ◽  
Camp Levels

Levels of cyclic 3',5'-cyclic monophosphate (cAMP) play an important role in the decision to enter the mitotic cycle in the yeast, Saccharomyces cerevisiae. In addition to growth arrest at stationary phase, S. cerevisiae transiently arrest growth as they shift from fermentative to oxidative metabolism (the diauxic shift). Experiments examining the role of cAMP in growth arrest at the diauxic shift show the following: 1) yeast lower cAMP levels as they exhaust their glucose supply and shift to oxidative metabolism of ethanol, 2) a reduction in cAMP is essential for traversing the diauxic shift, 3) the decrease in adenylate cyclase activity is associated with a decrease in the expression of CYR1 and CDC25, two positive regulators of cAMP levels and an increase in the expression of IRA1 and IRA2, two negative regulators of intracellular cAMP, 4) mutants carrying disruptions in IRA1 and IRA2 were unable to arrest cell division at the diauxic shift and were unable to progress into the oxidative phase of growth. These results indicate that changes cAMP levels are important in regulation of growth arrest at the diauxic shift and that changes in gene expression plays a role in the regulation of the Ras/adenylate cyclase system.

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