The Schizosaccharomyces pombe ran1/pat1 gene regulates the transition between mitosis and meiosis. Inactivation of Ran1 (Pat1) kinase is necessary and sufficient for cells to exit the cell cycle and undergo meiosis. The yeast two-hybrid interaction trap was used to identify protein partners for Ran1/Pat1. Here we report the identification of one of these, Cpc2. Cpc2 encodes a homologue of RACK1, a WD protein with homology to the ␤ subunit of heterotrimeric G proteins. RACK1 is a highly conserved protein, although its function remains undefined. In mammalian cells, RACK1 physically associates with some signal transduction proteins, including Src and protein kinase C. Fission yeast cells containing a cpc2 null allele are viable but cell cycle delayed. cpc2⌬ cells fail to accumulate in G 1 when starved of nitrogen. This leads to defects in conjugation and meiosis. Copurification studies show that although Cpc2 and Ran1 (Pat1) physically associate, Cpc2 does not alter Ran1 (Pat1) kinase activity in vitro. Using a Ran1 (Pat1) fusion to green fluorescent protein, we show that localization of the kinase is impaired in cpc2⌬ cells. Thus, in parallel with the proposed role of RACK1 in mammalian cells, fission yeast cpc2 may function as an anchoring protein for Ran1 (Pat1) kinase. All defects associated with loss of cpc2 are reversed in cells expressing mammalian RACK1, demonstrating that the fission yeast and mammalian gene products are indeed functional homologues.All living cells integrate signals from the environment to modify the activity of genes required for mitotic division, differentiation, or stationary phase. For the fission yeast Schizosaccharomyces pombe, nutritional signals direct life cycle choices. As key nutrients become limited, cells exit the mitotic cycle and enter either G 0 stationary phase or a program of sexual differentiation (6, 10). The choice between G 0 and differentiation is governed by the presence of mating-specific pheromones. Starved cells respond to pheromones produced by cells of the opposite mating type by undergoing transient G 1 arrest, followed by conjugation and meiosis (8,18,33,49). As expected from the need for both nutrient limitation and pheromone signaling, many signal transduction pathways converge to regulate differentiation. These include pathways regulated by cyclic AMP (cAMP), the ras1-regulated mitogen-activated protein (MAP) kinase pathway and the stress-activated MAP kinase pathway (see reference 51 for a review). However, a variety of studies indicate that each phase of the fission yeast life cycle can be governed by the activity of Ran1 (Pat1) kinase (referred to as Ran1 hereafter) and its substrates.Inactivation of Ran1 is necessary and sufficient to divert cells from the mitotic cell cycle into the meiotic developmental program (16,17,32). Experiments examining the phenotype of cells carrying a ran1 temperature-sensitive allele suggest that Ran1 is regulated by stepwise inactivation of the kinase (3, 23).Limiting nutritional conditions trigger partial inactivation ...

Major assets such as buildings, infrastructure and defence systems are long term investments that require many outsourced sustainment activities to maintain satisfactory performances over their service life. When multiplied by the number of years that the sustainment is planned to be undertaken, the contracting cost is high. Many business processes are established to govern these asset sustainment activities and eventually become the source of inefficiency. This paper analyses the performance of these processes using a performance driven approach. Combined with input data of requests for engineering change in similar assets, this paper evaluates a new business process redesigned from an existing process to achieve significant savings in total cost of ownership as well as improving other non-financial performance indicators.

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