Receptor Mediated Endocytosis Flashcards
Define pinocytosis
Invagination of membrane to form a vesicle to permit to uptake of extracellular solutes
Define endocytosis
The selective internalisation of molecules into the cell by binding to specific cell surface receptors
What is the name of the phagocytosis mechanism?
Zipping mechanism
What substance coats the pits on the membrane?
Clathrin
What are triskelions composed of?
Clathrin
Heavy chains
Light chains
How do we remove the clathrin coat?
ATP dependent uncoating protein
What could be going wrong in hypercholesterolaemia?
LDL receptors not localised over pits
Non-functional receptors
Receptor binding normal but no internalisation of receptors
How is the inside of the endosome different to the cytosol?
Lower pH (pH 6)
What happens to LDL and its receptor in the endosome?
They dissociate at this pH
What does CURL stand for?
Compartment of uncoupling of receptor and ligand
Endosome
Overall, what happens to the receptor and ligand in endocytosis of LDL?
Ligand (LDL) degraded
Receptor recycled
Define phagocytosis
Internalisation of particulate matter
What are ferric ions?
Fe3+
Do ferric ions bind directly to their receptor?
No
The bind apotransferrin first and then this complex binds to the receptor
What happens in the endosome for Fe3+ uptake?
Fe3+ already been released into cytosol
At endosome pH apotransferrin has a high affinity for the receptor so they stay bound and are both recycled
