School of Science Division of Life Science 10 Division of Life Science Mechanisms of Golgi Membrane Protein Retention Supervisor: BANFIELD David Karl / LIFS Student: LI Caifan / SSCI Course: UROP1100, Summer Vps74p provides a protein retention mechanism in Golgi to maintain the steady-state distribution of glycosyltransferases (GTs) and has always been an important topic in cell biology study. There have been many studies using fusion expression of fluorescent proteins assay showed that Vps74p bound both the binding motifs on the cytoplasmic tail of GTs and the COPI coat then achieved the protein retention in the Golgi. However, this method has limitations in the quantitative analysis of retained protein content. Thereby, in this report, we imitated a mammalian cell quantitative Golgi retention assay to demonstrate its applicability in yeast. However, our result showed when VPS74 was deleted, a reconstructed reporter protein with a Vps74p binding tail, which localized on the plasma membrane in wide-type cells (WT), could not go back to the plasma membrane as we expected but further accumulated in vacuoles. To improve the experiment, we excluded the interference of a mutation on the SI TMD, but the result was still not good. Finally, we offered several possible causes for this problem and a way to improve it. Studying Novel Cell Cycle Signalling Pathways in Yeast Cells Supervisor: BANFIELD David Karl / LIFS Student: SINCE Alec Victor / BIBU Course: UROP2100, Spring This literature review aims to investigate the role of TORC1 in regard to the various checkpoints in the cell cycle. This paper suggests that TORC1 is crucial for cell cycle progression due to its effect on the subcellular localization of a polo-kinase called Cdc5. Our lab used dcr2-6 ted1Δ yeast cells and made contradictory findings where we determined that TORC1 is required for spindle assembly checkpoint (SAC) activation at non-permissive temperatures in those strains. We came to this conclusion as the inhibition of TORC1 led to the inactivation of SAC. Further studies are required to determine whether Cdc5 also has an effect on dcr26 ted1Δ yeast cells. Studying Novel Cell Cycle Signalling Pathways in Yeast Cells Supervisor: BANFIELD David Karl / LIFS Student: YUK Tin Cheung / BTGBM Course: UROP1100, Fall GPI-Anchors contain mannose molecules, of which Man2 is attached to EtNP (Glycosylphosphatidylinositol) normally by the action of enzyme Gpi7p. After the attachment of EtNP to the GPI-Anchor protein, the Ted1p/Dcr2p enzymes would do the opposite to detach the EtNP from these GPI-Anchor proteins. Previously, it was found out that on the mutant strain of yeast(PGAL1GPI7ted1Δdcr2Δ), which lost the ability to produce Ted1p/Dcr2p enzyme, a lethal effect was demonstrated. This somehow revealed the toxicity of EtNP on the survival of cells.
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