plasma membrane fusion

Definition

Target type: biologicalprocess

The joining of the lipid bilayer membrane that surround a cell with that of another cell, producing a single cell. [GOC:elh, GOC:mtg_muscle]

Plasma membrane fusion is a fundamental biological process that allows cells to interact with their environment and communicate with each other. It involves the merging of two or more cellular membranes, creating a continuous membrane and enabling the exchange of materials and information. This process is essential for a wide range of cellular functions, including:

- **Exocytosis:** The release of cellular contents, such as hormones, neurotransmitters, and waste products, into the extracellular space.
- **Endocytosis:** The uptake of extracellular materials, such as nutrients, growth factors, and pathogens, into the cell.
- **Cell signaling:** The transmission of signals between cells, such as through the formation of synapses in the nervous system.
- **Cell division:** The separation of daughter cells during mitosis and meiosis.
- **Development:** The formation of tissues and organs during embryonic development.

The plasma membrane is a complex structure composed of a phospholipid bilayer, proteins, and carbohydrates. The process of membrane fusion is highly regulated and involves several key steps:

1. **Initiation:** The fusion process is triggered by specific signals, such as the binding of ligands to receptors on the cell surface.
2. **Approximation:** The two membranes approach each other and come into close proximity.
3. **Hemifusion:** The outer leaflets of the two membranes fuse, forming a single, continuous bilayer.
4. **Full fusion:** The inner leaflets of the two membranes fuse, creating a single, continuous membrane.

**Molecular Mechanisms:**

The fusion process is facilitated by specialized proteins called **SNAREs** (soluble N-ethylmaleimide-sensitive factor attachment protein receptors). SNARE proteins are found on both the target membrane and the vesicle membrane. They interact with each other to bring the two membranes into close proximity and promote fusion.

**Steps involved in SNARE-mediated fusion:**

1. **Translocation of SNAREs:** SNARE proteins from both the target and vesicle membranes translocate to the site of fusion.
2. **SNARE complex formation:** The SNARE proteins interact with each other to form a stable complex, bringing the membranes into close contact.
3. **Membrane fusion:** The SNARE complex promotes membrane fusion, leading to the formation of a single, continuous membrane.

**Regulation of Membrane Fusion:**

Membrane fusion is tightly regulated by a variety of factors, including:

- **Calcium:** Calcium ions play a critical role in triggering membrane fusion.
- **pH:** The pH of the environment can affect membrane fusion.
- **Lipid composition:** The composition of lipids in the membrane can influence fusion.
- **Other proteins:** Several other proteins, besides SNAREs, can regulate membrane fusion.

**Disruptions in Membrane Fusion:**

Disruptions in membrane fusion can lead to various diseases, including:

- **Neurological disorders:** Defects in membrane fusion can disrupt neurotransmission and lead to diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease.
- **Immune deficiencies:** Defective membrane fusion in immune cells can compromise the immune response and lead to immunodeficiency.
- **Viral infections:** Viruses can exploit membrane fusion to enter cells and spread infection.

In conclusion, plasma membrane fusion is a fundamental biological process that is essential for a wide range of cellular functions. The process is highly regulated and involves specialized proteins, such as SNAREs, which facilitate the merging of membranes. Disruptions in membrane fusion can lead to various diseases, highlighting the importance of this process for cell health and function.'
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Proteins (1)

Compounds (75)