golgi Flashcards
how do transport vesicles carry material?
they bud off from one compartment and fuse with another (carrying material as they go)
where does the secretory pathway lead?
outward from the ER to the golgi apparatus/cell surface
where does the endocytic pathway lead?
inward from the plasma membrane
what do transport vesicles form from?
from specialized coated regions of membranes
what are the four types of coated vesicles?
clathrin coated
COPI coated
COPII coated
retromer coated
what is the “coat” of coated proteins?
geometrical structures that assemble into vesicle cages
what do rab proteins do?
guide transport vesicles to their target membrane
what do SNARE proteins do?
mediate membrane fusion by putting membranes in close proximity
how do proteins leave the ER?
in COPII coated transport vesicles that form at ER exit site
what do cargo receptors inside vesicles do?
ensure the vesicles are loaded (recruit adaptor proteins that recruit the coat proteins
how do COPII vesicles accommodate large cargoes?
by assembling tubes instead of vesicles
what does the golgi consist of?
flattened, membrane-enclosed compartments called cisternae
what the destination codes at the golgi?
glycosylation and phosphorylation
what is the purpose of sugar coats?
destination tags, some are transient
how does transport through the golgi apparatus happen?
through vesicle transport molecules (between cisternae) or through cisternal maturate (from cis to trans with cargo molecules)
what evidence supports the vesicular model of golgi transportation?
vesicles bud and fuse
COPI vesicles surround the golgi
what evidence supports the maturation model of golgi transportation?
proto collagen is bigger than vesicles
PC is not detectable inside vesicles
it localizes to enlarged golgi cisternae
what do COPI vesicles do in golgi transportation?
bring ER proteins back from the golgi
what is the KDEL?
KDEL sequence in ER proteins and KDEl receptor initiates vesicle formation
what transports most proteins directly to cell surface?
nonselective consitituve secretory pathway
- no specific signal (doesn’t transport direct secretory proteins into secreotry vesicles or lysosomal proteins into different specialized transport vesicles)
