Lipoproteins like LDL and HDL transport lipids and proteins through the blood stream. Receptors on cells can bind to the lipoproteins and remove them from the blood, using the lipids for energy and to produce membranes. Which of the following mechanisms would be used to move a lipoprotein into a cell?
A) Active transport
B) Facilitated diffusion
C) Receptor-mediated endocytosis
D) Endocytosis
E) Exocytosis

Receptor-mediated endocytosis can be defined as the process in which when certain molecules or substances (lipoproteins) bind to their cognate receptors present on the surface of the cells, they are internalised into the cells by the inward protrusion of the plasma membrane into the cell followed by the pinching off of the membrane in the form of a vesicle.
The vesicle contains the lipoproteins bound to the receptors.
The lipoproteins are then targeted to the endosomes for recycling or other purposes.
The endocytosis process is mediated by specific structural proteins called the clathrin which line the inner plasma membrane beneath the lipoprotein receptors.
They help the plasma membrane to protrude into the cells and pinch off in the form of a vesicle.