L4 Anterograde vs Retrograde Protein Transport

what are the three main pathways for vesicle transport

secretory/exocytosis, endocytosis, retrieval/recycling

what are the types of endocytosis

molecular uptake : receptor-mediated

cell eat : phagocytosis

cell drink : pinocytosis

what do lysosomes contain that allows degradation

acid hydrolases

what is the difference between consecutive & regulated secretion

regulated secretion indicates that the cargo of the vesicle isn’t released until there is a receptor/ligand binding on the plasma which allows the cargo to be released into the extracellular matrix

what are the LDL/LDL receptor in endocytosis

1- LDL binds to its receptor on the plasma membrane

2- LDL is incorporated into clathrin-coated pits

3- vesicles bud off & fuse with early endosome

4- LDL is transported to lysosome and degraded, allowing cholesterol to be released

what is transferrin

a protein bound to iron

in the endosome w/ low pH, the iron dissociates & apoptransferrin recycles back to the plasma membrane

what is dynamin

a GTPase enzyme that is essential for pinching off vesicles that form from the plasma membrane (theres dynamin dependent & independent vesicles)

what are the steps of endocytosis

1- synthesis of receptors

2- random insertion in the plasma membrane

3- clustering of receptors in clathrin-coated pits

4- internalization of receptor-containing vesicles

5- recycling of receptors

what determines the levels of receptors in the plasma membrane

the differential rate of recycling to the plasma membrane & degradation in the lysosome (exocytosis & endocytosis occur concurrently)