Intracellular Vesicular Traffic 2 Flashcards
Lysosomes are heterogeneous - derived from _____ endosomes.
Late
Lysosomes are membrane enclosed compartments filled with _____ ______.
Hydrolytic enzymes
Lysosomes are important for _____ _____ of macromolecules
intracellular digestion
There are about 40 types of enzymes in lysosomes: name 7 acid hydrolases
Proteases, nucleases, glycosidses, lipases, phopsholipases, phosphatases, and sulfatases
Lysosome enzymes require ____ ______ and ____ _____ for optimal activation
acid environment
proteolytic cleavage
Lysosomal ________ protects cell against is enzymes.
membrane
________ in membrane pump out end products of digestion.
Transporters
_____ ______ pumps H+ into lysosomes to maintain the acidic pH and to drive transport of small metabolites.
Vacuolar ATPase
pH in lysosomes is about:
5.0
Transport from TGN to lysosomes uses the pathway that delivers _____ ______ and ______ to lysosomes.
Membrane proteins
hydrolases
Membrane proteins and hydrolases are co-translationally transported into ____ _____ and then transported via Golgi complex to _____.
Rough ER
TGN
TGN buds of into _______.
Endosomes
Endosomes develop into _______.
Lysosomes
Lysosomal hydrolases have _____-__-_____ attached to them in the ____.
mannose-6-phosphate (M6P)
CGN
____ ______ in TGN recognize the sugar.
M6P receptors
M6P receptors bind to hydrolases and adaptor proteins in assembling _____ coats. All packaged into ______-coated vesicles that bud from ____.
Clathrin, clathrin, TGN
Contents from TGN are delivered into ______ and then to _______.
Endosomes
Lysosomes
What enzyme transfers a phosphate to lysosomal hydrolase with terminal mannose residue?
GlcNAc phosphotransferase
end product is M6P
Lysosomal storage diseases arise from ___ ____ in lysosomal _______.
Genetic defects, hydrolases
In lysosomal storage disease, there is an accumulation of _____ _____ in lysomsomes.
undigested material
______ _____: mutation in the enzyme required to break down glycosaminoglycan chains.
Hurler’s disease
______ ____ ____: all of the lysosomal hydrolases are missing in fibroblasts.
Inclusion cell disease
Defective or missing _____ ________, an enzyme that adds _____ to lysosomal hydrolases, the enzymes are not _________ and hence not sorted into vesicles and not delivered into lysosomes.
They are instead secreted into _____.
GlcNAc phosphotransferase,
M6P
phosphorylated
Blood
Endocytosis: uptake of ______ from ______ across plasma membrane.
macromolecules
exterior
In endocytosis, material is ________ enclosed by a portion of the PM.
progressively
PM invaginates and then pinches off to form ______ ______.
Endocytoic vesicles
Large particles ingested by vesicles called phagosomes is a process called ______.
Phagocytosis
Small particles ingested pinocytic vesicles is a process called ______.
Pinocytosis
Receptor-mediated endocytosis is used to _____ select ______ from outside cell.
import
macromolecules
Endocytosis-
Molecules bind to _____ on membrane surface.
Receptors
Endocytosis-
Molecules accumulate in ____-_____ ____.
Clathrin-coated pits
Endocytosis-
Enters the cell as _____-______ complex in clathrin-coated vesicles
receptor-macromolecule
Receptor-macromolecular complex provides _____ _______ mechanisms.
selective concentration
An example of selective concentration mechanism is ____ _____.
Cholesterol uptake
Blockage of receptor-mediated endocytosis results in _______.
Atherosclerosis
_______ or ‘cell drinking’ is a constitutive process and occurs continuously in all eukaryotic cells.
Pinocytosis
Cells ____ ___ __ __ in the form of small pinocytic vesicles
Ingest bits of PM
Macrophages ingest about __% of its membrane every minute.
3
Pinocytosis process begins at ____-_____ ___.
Clathrin-coated pits
Membrane ______ and ______ ___ to form clathrin-coated vesicles.
invaginates and pinches off
During pinocytosis, what is trapped in the pits as they invaginate?
Extracellular fluid with various solutes
_____ clathrin-coated vesicles leave PM of a fibroblast every minute.
2500
_____: flask-shaped invaginations in PM.
Caveolae
Caveolae are enriched in _____ and _______, and GPI-anchored membrane proteins.
Cholesterol and glycosphingolipids
Major structural protein of caveolae is ______.
caveolin
Caveolae invaginate into membrane by virtue of ___ _______ and not the protein coat.
Lipid composition
Caveolae pinch off from PM by _____.
Dynamin
Caveolae pinched off from PM form ________.
Caveosome (endosome-like compartment)
Caveosome (do/dont) connect with lysosomes.
DO NOT
During the process of exocytosis, transport vesicles move from ____ to ___.
TGN to PM
A fusion of vesicles with PM is called _____.
Exocytosis
What are found in vesicles destined for PM?
Membrane proteins and lipids
______ proteins are secreted out of cells.
Soluble
________ secretory pathway operates continuously.
Constitutive
_______ secretory pathway triggered by signals.
Regulated
Protein sorting happens in the ____.
TGN
Proteins destined for secretion are packed into secretory vesicle in the ___.
TGN
Proteins destined for secretion packaging involves ______ ______/______ of proteins.
Selective aggregation/clumping
**mechanism not fully understood
Vesicle membrane proteins may have ______ for aggregated proteins or undergo phagocytosis like mechanism
Receptors
Proteins concentrated into vesicle by ____ of ____ _____ that go back to TGN and ER.
Retrieval of other proteins
TGN also promotes _____ _____ of the secretory proteins - activation mechanism
Proteolytic processing
