scholarly journals Adenylate cyclase in Saccharomyces cerevisiae is a peripheral membrane protein.

1990 ◽  
Vol 10 (8) ◽  
pp. 3873-3883 ◽  
Author(s):  
M R Mitts ◽  
D B Grant ◽  
W Heideman

The adenylate cyclase system of the yeast Saccharomyces cerevisiae contains the CYR1 polypeptide, responsible for catalyzing formation of cyclic AMP (cAMP) from ATP, and two RAS polypeptides, which mediate stimulation of cAMP synthesis of guanine nucleotides. By analogy to the mammalian enzyme, models of yeast adenylate cyclase have depicted the enzyme as a membrane protein. We have concluded that adenylate cyclase is only peripherally bound to the yeast membrane, based on the following criteria: (i) substantial activity was found in cytoplasmic fractions; (ii) activity was released from membranes by the addition of 0.5 M NaCl; (iii) in the presence of 0.5 M NaCl, activity in detergent extracts had hydrodynamic properties identical to those of cytosolic or NaCl-extracted enzyme; (iv) antibodies to yeast adenylate cyclase identified a full-length adenylate cyclase in both membrane and cytosol fractions; and (v) activity from both cytosolic fractions and NaCl extracts could be functionally reconstituted into membranes lacking adenylate cyclase activity. The binding of adenylate cyclase to the membrane may have regulatory significance; the fraction of activity associated with the membrane increased as cultures approached stationary phase. In addition, binding of adenylate cyclase to membranes appeared to be inhibited by cAMP. These results indicate the existence of a protein anchoring adenylate cyclase to the membrane. The identity of this protein remains unknown.

1990 ◽  
Vol 10 (8) ◽  
pp. 3873-3883
Author(s):  
M R Mitts ◽  
D B Grant ◽  
W Heideman

The adenylate cyclase system of the yeast Saccharomyces cerevisiae contains the CYR1 polypeptide, responsible for catalyzing formation of cyclic AMP (cAMP) from ATP, and two RAS polypeptides, which mediate stimulation of cAMP synthesis of guanine nucleotides. By analogy to the mammalian enzyme, models of yeast adenylate cyclase have depicted the enzyme as a membrane protein. We have concluded that adenylate cyclase is only peripherally bound to the yeast membrane, based on the following criteria: (i) substantial activity was found in cytoplasmic fractions; (ii) activity was released from membranes by the addition of 0.5 M NaCl; (iii) in the presence of 0.5 M NaCl, activity in detergent extracts had hydrodynamic properties identical to those of cytosolic or NaCl-extracted enzyme; (iv) antibodies to yeast adenylate cyclase identified a full-length adenylate cyclase in both membrane and cytosol fractions; and (v) activity from both cytosolic fractions and NaCl extracts could be functionally reconstituted into membranes lacking adenylate cyclase activity. The binding of adenylate cyclase to the membrane may have regulatory significance; the fraction of activity associated with the membrane increased as cultures approached stationary phase. In addition, binding of adenylate cyclase to membranes appeared to be inhibited by cAMP. These results indicate the existence of a protein anchoring adenylate cyclase to the membrane. The identity of this protein remains unknown.


1991 ◽  
Vol 11 (9) ◽  
pp. 4591-4598 ◽  
Author(s):  
M R Mitts ◽  
J Bradshaw-Rouse ◽  
W Heideman

The adenylate cyclase system of the yeast Saccharomyces cerevisiae contains many proteins, including the CYR1 polypeptide, which is responsible for catalyzing the formation of cyclic AMP from ATP, RAS1 and RAS2 polypeptides, which mediate stimulation of cyclic AMP synthesis by guanine nucleotides, and the yeast GTPase-activating protein analog IRA1. We have previously reported that adenylate cyclase is only peripherally bound to the yeast membrane. We have concluded that IRA1 is a strong candidate for a protein involved in anchoring adenylate cyclase to the membrane. We base this conclusion on the following criteria: (i) a disruption of the IRA1 gene produced a mutant with very low membrane-associated levels of adenylate cyclase activity, (ii) membranes made from these mutants were incapable of binding adenylate cyclase in vitro, (iii) IRA1 antibodies inhibit binding of adenylate cyclase to the membrane, and (iv) IRA1 and adenylate cyclase comigrate on Sepharose 4B.


1993 ◽  
Vol 4 (7) ◽  
pp. 757-765 ◽  
Author(s):  
M Russell ◽  
J Bradshaw-Rouse ◽  
D Markwardt ◽  
W Heideman

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.


1991 ◽  
Vol 11 (9) ◽  
pp. 4591-4598
Author(s):  
M R Mitts ◽  
J Bradshaw-Rouse ◽  
W Heideman

The adenylate cyclase system of the yeast Saccharomyces cerevisiae contains many proteins, including the CYR1 polypeptide, which is responsible for catalyzing the formation of cyclic AMP from ATP, RAS1 and RAS2 polypeptides, which mediate stimulation of cyclic AMP synthesis by guanine nucleotides, and the yeast GTPase-activating protein analog IRA1. We have previously reported that adenylate cyclase is only peripherally bound to the yeast membrane. We have concluded that IRA1 is a strong candidate for a protein involved in anchoring adenylate cyclase to the membrane. We base this conclusion on the following criteria: (i) a disruption of the IRA1 gene produced a mutant with very low membrane-associated levels of adenylate cyclase activity, (ii) membranes made from these mutants were incapable of binding adenylate cyclase in vitro, (iii) IRA1 antibodies inhibit binding of adenylate cyclase to the membrane, and (iv) IRA1 and adenylate cyclase comigrate on Sepharose 4B.


1982 ◽  
Vol 2 (12) ◽  
pp. 1481-1491
Author(s):  
Patrick K. Jaynes ◽  
James P. McDonough ◽  
Henry R. Mahler

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.


1985 ◽  
Vol 249 (2) ◽  
pp. F291-F298 ◽  
Author(s):  
J. M. Elalouf ◽  
N. Roinel ◽  
C. de Rouffignac

The effects of 1-desamino-8-D-arginine vasopressin (dDAVP) on the handling of water and electrolytes by the juxtamedullary nephrons were studied on rats with reduced circulating levels of antidiuretic hormone (ADH), parathyroid hormone, calcitonin, and glucagon, all of which stimulate the adenylate cyclase system of the thick ascending limb and the distal tubule. In such hormone-deprived rats and in hormone-deprived + dDAVP rats, the concentration of Na, Cl, and total solutes was lower in the ascending than in the descending limbs, whereas the inulin concentration was similar at both sites. dDAVP did not alter the fraction of NaCl remaining in the thin limbs, but tended to reduce that of Mg and Ca. On the other hand, dDAVP significantly increased the fraction of filtered K remaining from 65.8 +/- 5.2 to 107.3 +/- 15.8%. A direct correlation was observed between the fraction of filtered K remaining at the tip of the juxtamedullary loops and the fractional excretion rate of K in urine. Since dDAVP enhances distal K net secretion, as previously shown in our laboratory, these results indicate that the medullary recycling of K from nephron terminal segments to Henle's loop of juxtamedullary nephrons is stimulated by this peptide.


2016 ◽  
Vol 44 (2) ◽  
pp. 474-478 ◽  
Author(s):  
Chris MacDonald ◽  
Robert C. Piper

Sorting internalized proteins and lipids back to the cell surface controls the supply of molecules throughout the cell and regulates integral membrane protein activity at the surface. One central process in mammalian cells is the transit of cargo from endosomes back to the plasma membrane (PM) directly, along a route that bypasses retrograde movement to the Golgi. Despite recognition of this pathway for decades we are only beginning to understand the machinery controlling this overall process. The budding yeast Saccharomyces cerevisiae, a stalwart genetic system, has been routinely used to identify fundamental proteins and their modes of action in conserved trafficking pathways. However, the study of cell surface recycling from endosomes in yeast is hampered by difficulties that obscure visualization of the pathway. Here we briefly discuss how recycling is likely a more prevalent process in yeast than is widely appreciated and how tools might be built to better study the pathway.


2005 ◽  
Vol 4 (2) ◽  
pp. 281-288 ◽  
Author(s):  
Yoojin Kim ◽  
Subrata Chattopadhyay ◽  
Sarahjane Locke ◽  
David A. Pearce

ABSTRACT Btn2p, a novel cytosolic coiled-coil protein in Saccharomyces cerevisiae, was previously shown to interact with and to be necessary for the correct localization of Rhb1p, a regulator of arginine uptake, and Yif1p, a Golgi protein. We now report the biochemical and physical interactions of Btn2p with Ist2p, a plasma membrane protein that is thought to have a function in salt tolerance. A deletion in Btn2p (btn2Δ strains) results in a failure to correctly localize Ist2p, and strains lacking Btn2p and Ist2p (btn2Δ ist2Δ strains) are unable to grow in the presence of 0.5 or 1.0 M NaCl. Btn2p was originally identified as being up-regulated in a btn1Δ strain, which lacks the vacuolar-lysosomal membrane protein, Btn1p, and serves as a model for Batten disease. This up-regulation of Btn2p was shown to contribute to the maintenance of a stable vacuolar pH in the btn1Δ strain. Btn1p was subsequently shown to be required for the optimal transport of arginine into the vacuole. Interestingly, btn1Δ ist2Δ strains are also unable to grow in the presence of 0.5 or 1.0 M NaCl, and ist2Δ suppresses the vacuolar arginine transport defect in btn1Δ strains. Although further investigation is required, we speculate that altered vacuolar arginine transport in btn1Δ strains represents a mechanism for maintaining or balancing cellular ion homeostasis. Btn2p interacts with at least three proteins that are seemingly involved in different biological functions in different subcellular locations. Due to these multiple interactions, we conclude that Btn2p may play a regulatory role across the cell in response to alterations in the intracellular environment that may be caused by changes in amino acid levels or pH, a disruption in protein trafficking, or imbalances in ion homeostasis resulting from either genetic or environmental manipulation.


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