L9 Yeast Screens Flashcards
Enzyme modifications
glycosylation and proteolytic cleavage
What are the major membrane trafficking pathways
secretory/exocytic pathway, endocytic pathway
What is NOT part of the secretory pathway
mitochondria
What does the secretory pathway involve
ER to golgi to PM/endosome/lysosome
What does the endocytic pathway involve
cell surface to endosome to golgi/ER/lysosom
Protein modification as they transit ER and golgi
glycosylated and proteolytically cleaved
Advantage of yeast as model organism for membrane trafficking studies
genome sequenced, cheap and easy to grow, large quantities
Disadvantages of yeast as model organism
limited cell-cell contact, small, cell wall
Aim of Novick and Schekman experiment in 1980
investigate secretory pathway in yeast
Secretory mutants
fail to export active invertase and acid phosphatase
Difference in mutant appearance
accumulation of vesicles, aberrant membranous structures
How many genes are involved in transport of proteins to membrane
23
Where do secreted proteins from class A sec genes accumulate
cytosol
Where do secreted proteins from class B sec genes accumulate
rough ER
Where do secreted proteins from class C sec genes accumulate
ER to golgi transport vesicles
Where do secreted proteins from class D sec genes accumulate
golgi
What genes did Novick and Schekman miss?
genes involved in transport to endosome or vacuole, redundantly functioning genes
Where is the decision made to traffic to surface or lysosome
TGN
What is endocytosis
PM invaginates into the cell - vesicle production that fuses with endosome
Endocytosis functions
down-regulation of signals, remodelling cell surface composition
What is the first stage of endocytosis
PM to endocytic vesicle
What is the last stage of endocytosis
late endosome to golgi or vacuole
What is important in yeast endocytosis
actin cytoskeleton
What is the major function of lysosomes
degradation of extracellular material
What do lysosomes contain
degradative/proteolytic enzymes
What is carboxypeptidase
vacuolar enzyme
where is carboxypeptidase transported from
ER to golgi
How is carboxypeptidase sorted
by receptors
What does the transport step of sorting require
cytoplasmic factors
What cytoplasmic factors does the transport step of sorting require
clathrin and two adaptors called Gga1 Gga2
