Down
regulation
o
Is the process by which a cell decreases the quantity of a
cellular component, such as RNA or protein in response to an external variable.
o
There are several ways in which a cell down regulates its cellular
components.
1. Receptor
mediated endocytosis.
Occurs when the material to be transported into the cell binds to
certain specific molecules in the membrane. Common cause for down regulation in
membrane receptor.
2. Internalization.
Ligands bind to their receptors and ligand-receptor complex move
laterally in the membrane to coated pits where they are taken into the cell by
endocytosis. Some receptors are recycled and some replaced by de nova
synthesis.
