Vesicle fusion

Vesicle fusion is a fundamental process in cell biology that involves the merging of a vesicle with other vesicles or with a cellular membrane. This process is crucial for a variety of cellular functions, including protein trafficking, neurotransmitter release, and cell secretion.

Mechanism of Vesicle Fusion

Vesicle fusion is mediated by a group of proteins known as SNAREs (Soluble NSF Attachment Protein Receptors). These proteins are found on both the vesicle membrane (v-SNAREs) and the target membrane (t-SNAREs). The interaction between v-SNAREs and t-SNAREs pulls the two membranes together, causing them to fuse.

The process of vesicle fusion can be divided into several steps:

1. Docking: The vesicle approaches the target membrane and is captured by Rab proteins, a family of small GTPases.
2. Priming: The vesicle is prepared for fusion by the action of Sec1/Munc18-like (SM) proteins and SNARE proteins.
3. Fusion: The vesicle and target membranes merge, releasing the vesicle's contents into the target compartment or the extracellular space.

Role in Cellular Functions

Vesicle fusion plays a critical role in many cellular functions:

1. Protein Trafficking: Vesicle fusion is essential for the transport of proteins from the endoplasmic reticulum to the Golgi apparatus, and from there to other cellular compartments or the cell surface.
2. Neurotransmitter Release: In neurons, vesicle fusion is responsible for the release of neurotransmitters into the synaptic cleft, a process that is essential for neuronal communication.
3. Cell Secretion: Many cells secrete hormones, enzymes, and other substances by fusing vesicles with the plasma membrane.

Diseases Associated with Vesicle Fusion

Defects in vesicle fusion can lead to a variety of diseases, including neurodegenerative diseases like Alzheimer's disease and Parkinson's disease, and metabolic diseases like diabetes.

See Also

• Endocytosis
• Exocytosis
• Membrane transport
• SNARE (protein)

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  Exocytosis machinery involved in vesicle fusion
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  Membrane fusion via stalk formation