Cholesterol is transported in the blood in various lipoprotein complexes

LDL- low density lipoproteins

HDL- high density lipoproteins

cholesterol esterifed to fatty acid

Receptors of the surface of target cells bind to the apoB protien of LDL. This initiates endocytosis.


After endocytosis the LDL is inside the cell and surrounded by membrane

The vesicle containing the LDL fuses with another vesicle called the Compartment for the Uncoupling of Receptor and Ligand (CURL)

Fusion of the CURL and LDL vesicle causes the apoB protein and the receptor to change shape because of the low (pH 5) pH.

The receptor is recycled back to the plasma membrane and the endocytotic vesicle containing the LDL fuses with a primary lysosome.

The LDL is degraded by the acid hydrolyases of the lysosome and the amino acids, cholesterol and fatty acids are recoved in the cytosol.

Annimation of the above process