vesicle budding from membrane

Definition

Target type: biologicalprocess

The evagination of a membrane, resulting in formation of a vesicle. [GOC:jid, GOC:tb]

Vesicle budding is a fundamental cellular process that involves the formation of small, membrane-bound vesicles from a larger donor membrane. This process is essential for various cellular functions, including protein trafficking, signal transduction, and membrane remodeling. Here's a detailed description of the biological process of vesicle budding:

1. **Initiation:** Vesicle budding starts with the recruitment of specific proteins to the donor membrane, forming a bud initiation site. These proteins include:
* **Coat proteins:** These proteins assemble on the cytosolic surface of the donor membrane, shaping the nascent vesicle and driving its formation. Different types of coat proteins are involved in different vesicle budding pathways, such as clathrin, COPI, and COPII.
* **Adaptor proteins:** These proteins bind to cargo molecules and interact with coat proteins, linking the cargo to the budding vesicle.
* **Small GTPases:** These proteins act as molecular switches, regulating the assembly and disassembly of coat proteins and other components of the budding machinery.

2. **Membrane deformation:** As coat proteins assemble, they begin to curve the membrane, forming a bud. This deformation is driven by several factors:
* **Protein-protein interactions:** Coat proteins interact with each other and with the membrane, leading to membrane curvature.
* **Lipid modifications:** The lipid composition of the donor membrane can influence its curvature. Some lipids promote membrane bending, while others resist it.
* **Mechanical forces:** The cytoskeleton can provide mechanical force to aid in vesicle budding.

3. **Cargo selection:** During budding, specific cargo molecules, such as proteins, lipids, or even other organelles, are selectively packaged into the forming vesicle. This selection is crucial for the accurate delivery of cargo to its destination.

4. **Scission:** Once the bud has reached a certain size and shape, it needs to be pinched off from the donor membrane. This process, known as scission, involves the recruitment of specific proteins that sever the connection between the vesicle and the donor membrane. Several proteins are involved in this step, including:
* **Dynamin:** This protein forms a ring around the neck of the bud, and through GTP hydrolysis, it constricts the neck, ultimately leading to vesicle fission.
* **Other scission proteins:** These proteins work in conjunction with dynamin to facilitate the final separation of the vesicle.

5. **Uncoating:** After scission, the vesicle often sheds its coat proteins, which are then recycled back to the donor membrane for subsequent budding events. This uncoating allows the vesicle to interact with its target membrane and deliver its cargo.

Overall, vesicle budding is a complex and highly regulated process that is critical for maintaining cellular function. This intricate process involves the coordinated action of numerous proteins and lipid modifications to ensure accurate cargo selection, vesicle formation, and efficient delivery of cargo to its final destination.'
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Proteins (3)

Compounds (20)