Exocytosis is the process by which intracellular vesicles fuse with the plasma membrane and release their contents into the extracellular fluid. The steps of exocytosis include the following:

• Trafficking – vesicles carrying content are transported to the plasma membrane using motor proteins and the cytoskeleton.
• Tethering – once the vesicles have reached the plasma membrane Rab proteins on the vesicle recognize and link to tethering proteins on the plasma membrane.
• Docking – v-SNARE proteins on the vesical bind to complimentary t-SNARE proteins on the plasma membrane.
• Priming – this step occurs only in regulated exocytosis in which the cell membrane undergoes modifications to facilitate exocytosis.
• Fusing – v-SNARE and t-SNARE proteins tightly wrap around each other bringing the vesical into contact with the plasma membrane which forces them to fuse together.