Regulation in Yeast

Burd, C., Babst, M., and Emr, S. (1998). Novel pathways, membrane coats and PI kinase regulation in yeast lysosomal trafficking. Semin. Cell Dev. Biol. 9, 527—533. 

Gene Regulation in Yeast A Unicellular Eukaryote Galactose Metabolism Is Regulated by Specific Positive and Negative Control Factors in Yeast The GAL4 Protein Is Separated into Domains with Different Functions... 

Struhl, K., Molecular mechanisms of transcriptional regulation in yeast. Ann. Rev. Biochem. 58 1051-1077, 1989. 

All of these observations give evidence for the important role of PolyPs in cell cycle regulation in yeast. 

The final step in the acylation of Ras is the formation of a palmitoylester bond with a cysteine. Palmitoylation is reversible and could be subject to regulation. In yeast cells, where the protease that removes the COOH-terminal AAX sequence has been deleted by mutation, Ras can not be palmitoylated. In these cells Ras has lost its orientation and ends up in the interior of the cell, rather than at the plasma membrane. Therefore it is thought that farnesylation may target Ras quite indiscriminately to all kinds of cellular membranes, including endoplasmic membranes, and that only palmitoylation traps Ras in the plasma membrane, where the palmitoyl transferase is localized. 5... 

Finally, the phosphorylation of IREl has been shown to be down-regulated in yeast by the protein phosphatase Ptc2 (Welihinda et al. 1998 Valkonen et al. 2004) and more recently, a phospho-tyrosine dependent regulation of IREl signaling has been demonstrated through the potentiating role of the phospho-tyrosine phosphatase PTP-IB (Guet al. 2004). 

We can now compare the discovered motifs with our prior knowledge about transcriptional regulation in yeast. 

A protein-counting mechanism for telomere length regulation in yeast. Science 275, 986— 990. 

The abundance of many protein kinases in cells is an indication of the great importance of protein phosphorylation in cellular regulation. Exactly 113 protein kinase genes have been recognized in yeast, and it is estimated that the human genome encodes more than 1000 different protein kinases. Tyrosine kinases (protein kinases that phosphorylate Tyr residues) occur only in multicellular organisms (yeast has no tyrosine kinases). Tyrosine kinases are components of signaling pathways involved in cell-cell communication (see Chapter 34). 

PEP carboxylase occurs in yeast, bacteria, and higher plants, but not in animals. The enzyme is specifically inhibited by aspartate, which is produced by transamination of oxaloacetate. Thus, organisms utilizing this enzyme control aspartate production by regulation of PEP carboxylase. Malic enzyme is found in the cytosol or mitochondria of many animal and plant ceils and is an NADPIT-dependent enzyme. 

Sorger, P.K., Lewis, M.J., Pelham, H.B.R. (1987). Heat shock factor is regulated differently in yeast and HeLa cells. Nature 329, 81-84. 

Malik, S. and R.G. Roeder. Transcriptional regulation through mediator-like coactivators in yeast and metazoan cells. Trends Biochem. Sci. 2000, 25, 277-283. 

The multiple sites that serve as origins for DNA replication in eukaryotes are poorly defined except in a few animal viruses and in yeast. However, it is clear that initiation is regulated both spatially and temporaUy, since clusters of adjacent sites initiate rephcation synchronously. There are suggestions that functional domains of chromatin replicate as intact units, implying that the origins of rephcation are specificaUy located with respect to transcription units. 

A rather satisfactory explanation of the irreversibility of amino acid accumulation in yeast cells is that it might result from specific regulatory mechanisms capable of immobilizing the transporters in a closed position. Uptake of amino acids by a number of permeases does indeed appear to be regulated by specific, and possibly allosteric, feedback inhibition. This idea is based on the fact that a number of transport systems seem to be specifically inhibited by their internally accumulated... 

D. Hide, M. Broderius, J. Fett, and M. L. Guerinot, A novel iron-regulated metal transporter from plants identified by functional expression in yeast. Proc. Natl. Acad. Sci. U.S.A. 93 5624 (1996). 

Fosburg, S. L., and Nurse, P. (1991). Cell cycle regulation in the yeasts Saccharomyces cerevisiae and Schizosaccaromycespombe. Annu, Rev. Cell Biol. 7 227-256. 

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