Nucleus Saccharomyces cerevisiae

Fig. 2.3 The development of polarity and asymmetric division in Saccharomyces cerevisiae. The diagram is reproduced in a slightly simplified form from the work of Lew Reed (1995) with the permission of Current Opinion in Genetics and Development, (a) The F-actin cytoskeleton strands = actin cables ( ) cortical actin patches, (b) The polarity of growth is indicated by the direction of the arrows (arrows in many directions signifies isotropic growth), (c) 10-nm filaments which are assembled to form a ring at the neck between mother and bud. (d) Construction of the cap at the pre-bud site. Notice that the proteins of the cap become dispersed at the apical/isotropic switch, first over the whole surface of the bud, then more widely. Finally, secretion becomes refocussed at the neck in time for cytokinesis, (e) The status and distribution of the nucleus and microtubules of the spindle. Notice how the spindle pole body ( ) plays an important part in orientation of the mitotic spindle.

Fig. 2.6 The moqjhological events of sporulation in Saccharomyces cerevisiae. (a) starved cell V, vacuole LG, lipid granule ER, endoplasmic reticulum CW, cell wall M, mitochondrion S, spindle pole SM, spindle microtubules N, nucleus NO, nucleolus, (b) Synaptonemal complex (SX) and development of polycomplex body (PB) along with division of spindle pole body in (c). (d) First meiotic division which is completed in (e). (f) Prepararation for meiosis II. (g) Enlargement of prospore wall, culminating in enclosure of separate haploid nuclei (h). (i) Spore coat (SC) materials produced and deposited, giving rise to the distinct outer spore coat (OSC) seen in the completed spores of the mature ascus (j). Reproduced from the review by Dickinson (1988) with permission from Blackwell Science Ltd.

Since the enzymatic activity of Ela was independent from increased phosphorylation the function of El phosphorylation remains unclear. From the three El homologs in the yeast Saccharomyces cerevisiae only Uba2p harbors a putative NLS. Uba2p is largely localized to the nucleus (Dohmen et al. 1995) and was shown to be essential for Smt3p-activation (Johnson et al. 

Forsburg, S. L., and L. Guarente, Communication between mitochondria and the nucleus in regulation of cytochrome genes in the yeast Saccharomyces cerevisiae. Ann. Rev. Cell. Biol. 5 153-180, 1989. 

The intracellular signal transduction pathway by which the yeast [16, 17] Saccharomyces cerevisiae responds to the presence of peptide mating pheromone in its surroundings is one of the best understood signalling pathways in eukaryotes, yet continues to generate new surprises and insights. The signal is transmitted from the cell-surface receptor-coupled G protein, via a MAP kinase cascade, to the nucleus. 

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