Vesicle Transport

Vesicle transport is an active and thus energy consuming process that the cell uses in order to capture or release macromolecules into or out of the cell.

While exocytosis helps release content like proteins, waste products or toxins to the outside of the cell via vesicles that are formed in the Golgi apparatus and then fused with the plasma membrane, endocytosis aims to capture substances by enclosing them in vesicles resulting from cell membrane folding.

Endocytosis

Depending on the content to engulf, endocytosis can be divided in phagocytosis, receptor-mediated endocytosis, and pinocytosis.

As we showed in our Macrophages – the big eater’s post, phagocytosis is a crucial process in macrophages, as it allows them to get rid of microbes, thus playing a role in cell immunity. This cell eating of solid material results in the formation of phagosomes, which are vesicles coming from the evagination of the cell membrane that will fuse with lysosomes carrying the enzymes required to break the engulfed substances.

When instead of solid particles it is liquid material encapsulated and internalised by the cell we can differentiate between receptor-mediated endocytosis and pinocytosis… but what is the difference between them? While receptor-mediated endocytosis has specificity in the captured substances, pinocytosis is a non-specific cell drinking1.