Exocytosis- Definition, Process and Types with Examples


Exocytosis is a process of cellular secretion or excretion in which material or substances contained in vesicles or sacs are released from the cell by fusion of the vesicular membrane with the cell membrane and extrusion of the contents to the exterior of the cell . It is a form of bulk transport and the opposite of endocytosis . Exocytosis occurs via secretory portals at the cell membrane called porosomes.

Exocytosis is an important process for many biological functions, such as:

  • Removing waste materials from the cell
  • Transporting hormones and proteins to their target cells
  • Chemical signaling between cells
  • Rebuilding the cell membrane by fusing lipids and proteins removed through endocytosis back into the membrane

Exocytosis requires energy and is therefore a type of active transport. The energy is mainly provided by ATP molecules that power the movement of vesicles along the cytoskeleton and the fusion of vesicles with the cell membrane.

In this article, we will explore the comparison of exocytosis with endocytosis, the mechanism of exocytosis, the types of exocytotic vesicles, the types of exocytosis, the steps involved in exocytosis, and some examples of exocytosis in different cells.