Exam 1 Flashcards
Briefly explain the process of protein glycosylation in yeast (e.g. which proteins
are glycosylated, where does glycosylation occur, glycosylation sites)
- recognition of signal sequence at ER, co-translational translocation into ER
- recognition of Asn-X-Ser glycosylation site while translocated into ER, transfer
of core oligosaccharide onto Asn (N-linked) from membrane-bound dolichol
carrier - subsequent trimming – Calnexin/Clareticulin cycle – cleavage of terminal
glucose residues leaving mannose residues exposed - further trimming during passage through ER, Golgi until final secretion
What is the purpose of protein glycosylation in Eukaryotes?
Trafficking through ER and golgi – secretion or to other organelles.
Protein quality control – folding, disulfide bridge formation, further posttranslational
modifications.
True or False: Proteins that are typically secreted by their native hosts are more stable than
intracellular proteins.
TRUE
True or False: Hypermannosylation of recombinant proteins is a common feature among
Saccharomyces, Pichia and Aspergillus expression systems.
FALSE: Hypermannoslation occurs in prokaryotes, NOT eukaryotes (all of those species are fungi)
True or False: Gene expression in Saccharomyces cerevisiae is under negative control
FALSE: Saccharomyces is a eukaryote, thus its gene expression is under POSITIVE control
True or False: A modified Ti-plasmid is used to transform plant cells
TRUE
True or False: Pichia pastoris is a crabtree positive yeast
FALSE: It is crabtree negative
True or False: Mating type switch is a characteristic of homothallic Saccharomyces strains
TRUE