Intracellular Vesicular Traffic 2 Flashcards
In lysosomes what are the membrane enclosed compartments filled with
Hydrolytic enzymes
What are important for intracellular digestion of macromolecules
Lysosomes
Name seven different types of enzymes found in lysosomes
- proteases
- nucleases
- glycosidases
- lipases
- phospholipases
- phosphatases
- sulfatases
What are two conditions in lysosomes that allow optimal activation of the contained enzymes
acidic environment
proteolytic cleavage
What pumps H+ into lysosomes to maintain the acidic pH to drive transport of small metabolites
Vacuolar ATPase
Transport from TGN to lysosomes is a pathway that delivers ____ to lysosomes
Membrane proteins
hydrolases
Lysosomal hydrolases have _____ attached to them in the CGN
mannose-6-phosphate
What receptors in the TGN recognize mannos-6-phosphate
M6P receptors
What are the steps of sorting Lysosomal proteins
- M6P in TGN recognize the sugar on lysosomal hydrolyses
- receptor bind to hydrolases & adaptor proteins in assembling clathrin coats
- proteins packaged into clathrin coated vesicles
- Contents delivered into endosomes and then to lysosomes
What disease is the result in a mutation in the enzyme required to break down glycosaminoglycan chains
Hurler’s Disease
What disease is the result of all of the lysosomal hydrolases missing in fibroblasts
Inclusion Cell Disease
What is the result of defective or missing GlcNAc phosphitransferase
GlcNAc is an enzyme that add M6P to lysosomal hydrolyses
- the enzymes won’t be phosphorylated and can’t be sorted into vesicles and can’t be delivered to lysosomes
- Instead the are secreted into the blood
Uptake of macromolecules from exterior across plasma membrane is called
Endocytosis
What is formed when the plasma membrane invaginated and pinches off
endocytic vesicle
When large particles are ingested by vesicles called phagasomes
phagocytosis
When small particles ingested by pinocytoc vesicles
pinocytosis
Describe receptor-mediated endocytosis
- used to import select macromolecules
- molecules bind to receptors
- accumulate in clathrin-coated pits
- enter cell as receptor-macromolecular complex
- *blockage of this pathway results in atherosclerosis
What type of endocytosis provides a selective concentration mechanism
Receptor-mediated endocytosis
Give one example of receptor-mediated endocytosis
cholesterol uptake
What is the main function of phagocytosis
- Ingestion of invading microorganisms to protect against infection
- scavenge senescent cells and apoptotic cells
What fuses with lysosomes and allows the degradation of ingested material
phagosomes
List some of the key mechanisms of phagocytosis
- triggered by binding of particle to receptors on phagocyte surface
- antibodies bind to microbe
- binding trigger formation of pseudopod
- pseudopod engulfs particle and forms phagosome
Pseudopod formation is driven by the localization of _____
actin polymerization and reorganization
What controls actin polymerization and reorganization
Rho GTPases and phosphoinositide signaling
