Sign In

Exocytosis is used to release material from cells. Like other bulk transport mechanisms, exocytosis requires energy.

While endocytosis takes particles into the cell, exocytosis removes them. Sometimes, the released material are signaling molecules. For example, neurons typically use exocytosis to release neurotransmitters. Cells also use exocytosis to insert proteins, such as ion channels, into their cell membranes, secrete proteins for use in the extracellular matrix, or release waste.

There are two main types of exocytosis in eukaryotes: regulated and non-regulated (or constitutive). Regulated exocytosis, which requires an external signal, is used to release neurotransmitters and secrete hormones. Unlike regulated exocytosis, constitutive exocytosis is carried out by all cells. Cells use constitutive exocytosis to release components of the extracellular matrix or incorporate proteins into the plasma membrane.

There are five major steps in regulated exocytosis and four in constitutive exocytosis.

The first step is vesicle trafficking, in which vesicles transport material to the plasma membrane. Motor proteins actively move vesicles along cytoskeletal tracks of microtubules and filaments. The second step is vesicle tethering, in which vesicles are linked to the plasma membrane. In the third step, vesicle docking, the vesicle membrane attaches to the plasma membrane, and the two membranes begin to merge.

The fourth step, vesicle priming, occurs only in regulated exocytosis. Vesicle priming includes modifications occurring after the vesicle docks but before it releases its contents. Priming prepares vesicles for fusion with the plasma membrane.

The fifth step is vesicle fusion. Vesicle fusion can be complete or kiss-and-run. In complete fusion, vesicles entirely collapse and become part of the plasma membrane, expelling their contents from the cell in the process. In kiss-and-run fusion, the vesicle is recycled: It only temporarily fuses with the plasma membrane, releases its contents, and returns to the cell’s interior.

Tags

ExocytosisEukaryotic CellMembrane bound VesiclesPlasma MembraneTransport VesicleGolgi ApparatusTrans golgi NetworkTargetExtracellular SpaceBulk Transport MechanismsEnergyEndocytosisSignaling MoleculesNeurotransmittersIon ChannelsCell MembranesExtracellular MatrixWasteRegulated ExocytosisNon regulated Exocytosis

From Chapter 5:

article

Now Playing

5.16 : אקסוציטוזיס

Membranes and Cellular Transport

65.7K Views

article

5.1 : מהם קרומים?

Membranes and Cellular Transport

146.2K Views

article

5.2 : נזילות הקרום

Membranes and Cellular Transport

148.7K Views

article

5.3 : מודל הפסיפס הנזיל

Membranes and Cellular Transport

138.2K Views

article

5.4 : מהו הפרש אלקטרוכימי?

Membranes and Cellular Transport

107.9K Views

article

5.5 : דיפוזיה

Membranes and Cellular Transport

182.6K Views

article

5.6 : אוסמוזה

Membranes and Cellular Transport

155.2K Views

article

5.7 : מתח בחיות

Membranes and Cellular Transport

115.6K Views

article

5.8 : מתח בצמחים

Membranes and Cellular Transport

52.6K Views

article

5.9 : קישורי חלבון

Membranes and Cellular Transport

65.4K Views

article

5.10 : תובלה בעלת סיוע

Membranes and Cellular Transport

122.4K Views

article

5.11 : תובלה פעילה ראשונית

Membranes and Cellular Transport

172.1K Views

article

5.12 : תובלה פעילה שניונית

Membranes and Cellular Transport

116.2K Views

article

5.13 : אנדוציטוזיס מתווך על ידי קולטנים

Membranes and Cellular Transport

103.0K Views

article

5.14 : פינוציטוזה

Membranes and Cellular Transport

64.8K Views

See More

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2025 MyJoVE Corporation. All rights reserved