Receptor-mediated endocytosis and phagocytosis are both cellular processes involved in the internalization of material into a cell. However, they differ in a few key ways.
Receptor-mediated endocytosis is a selective process in which specific molecules, such as hormones or growth factors, are taken into a cell by binding to specific receptors on the cell surface. The receptors with the bound ligand then become coated with clathrin, a protein, and are internalized into the cell through invagination of the plasma membrane. The clathrin-coated vesicle then travels to the interior of the cell, where the clathrin is removed and the ligand-receptor complex is delivered to a specific destination within the cell, such as the endoplasmic reticulum or the Golgi apparatus.
Phagocytosis, on the other hand, is the process by which cells, such as macrophages and neutrophils, take in solid particles, such as bacteria and cellular debris, by engulfing them. This process begins with the formation of pseudopods, extensions of the plasma membrane, which wrap around the particle and bring it into the cell. The membrane then closes around the particle, forming a phagosome, which then fuses with lysosomes to form a phagolysosome, where the contents of the phagosome are degraded and processed.