<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments"^^ . "An important function of lipids is their ability to form membrane bilayers. Membrane properties such as thickness, fluidity or curvature depend on the lipid composition, which varies among species, tissues, cells and organelles and even between membrane domains. Membranes are cellular barriers but also provide a matrix for proteins and chemical reactions and their properties can affect protein localizations, and enzyme activities of embedded proteins. Most known glycosylation enzymes are integral membrane proteins, that catalyze glycosylation reactions at the ER and Golgi membranes.\r\nWith this project, I aimed to study a regulative role of lipids in glycosylation processes. I chose the integral membrane protein Dolichol phosphate mannose synthase (Dpm1) from yeast as a model protein. Dpm1 is an essential protein in eukaryotes, and dysfunction of Dpm1 in vivo leads to hypoglycosylation and severe glycosylation defects. The glycosyltransferase catalyzes the synthesis of the mannosyl donor DolP Man which is required for all protein glycosylation routes. \r\nTo investigate a role of membrane lipids in modulating the activity of Dpm1, I used a liposomal reconstitution system. I established a purification and liposomal reconstitution protocol and developed an assay to study the enzymatic activity of yeast Dpm1 in vitro. The liposomal lipid composition was then systematically varied, to investigate the effect of the membrane lipids on the enzyme activity of Dpm1. The system was then extended by reconstituting of Dpm1 together with other proteins to study their interaction in different lipid environments. I found that the enzymatic activity of Dpm1 is modulated by the lipid composition of the membrane. An increase in DolP Man formation was observed at increased membrane fluidity and in the presence of phosphatidylethanolamine. In addition, I showed that yeast Dpm2 (Yil102c-A) can stimulate Dpm1 activity, independently of the membrane environment. By including the O mannosyl transferase Pmt4 from yeast or C. thermophilium, I successfully reconstituted O mannosylation in liposomes, where the DolP Man substrate for Pmt4 is provided by the enzymatic activity of Dpm1, demonstrating a successful in vitro reconstitution of a coupled enzyme chain reaction. With this work, I have provided the basis for further studies to investigate the role of lipids in regulating the activity of in vitro reconstituted enzyme reaction chains of glycosylation."^^ . "2023" . . . . . . . "Frauke"^^ . "Kikul"^^ . "Frauke Kikul"^^ . . . . . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments (PDF)"^^ . . . "PhDThesis_FraukeKikul.pdf"^^ . . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments (Other)"^^ . . . . . . "preview.jpg"^^ . . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments (Other)"^^ . . . . . . "medium.jpg"^^ . . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments (Other)"^^ . . . . . . "small.jpg"^^ . . . "The influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #34034 \n\nThe influence of membrane lipids on glycosylation processes: Activity of Dpm1 in different lipid environments\n\n" . "text/html" . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .