intermembrane lipid transfer

Definition

Target type: biologicalprocess

The transport of lipids between membranes in which a lipid molecule is transported through an aqueous phase from the outer leaflet of a donor membrane to the outer leaflet of an acceptor membrane. This process does not require metabolic energy and can be either spontaneous or mediated by lipid transfer proteins (LTPs). [GOC:krc, PMID:20823909, PMID:24220498, PMID:25797198]

Intermembrane lipid transfer is a crucial process in cellular function, involving the movement of lipids between different membrane compartments. This intricate process is essential for maintaining membrane integrity, regulating signaling pathways, and facilitating various cellular processes.

The transfer of lipids between membranes can occur through several mechanisms, including:

1. **Vesicular transport:** This involves the budding and fusion of vesicles, small membrane-enclosed compartments that carry lipids from one membrane to another. This process is highly regulated and involves specific proteins that mediate vesicle formation, trafficking, and fusion.

2. **Lipid transfer proteins:** These proteins facilitate the movement of individual lipid molecules across membranes. They bind to lipids on one membrane, diffuse through the aqueous environment, and release the lipids on the other membrane. Examples include phospholipid transfer proteins (PLTPs) and sterol carrier protein 2 (SCP2).

3. **Membrane contact sites:** These are specialized regions where two membranes come into close proximity, allowing for direct lipid exchange. These sites often contain specific proteins that mediate lipid transfer and may involve the formation of transient channels or pores.

The direction of lipid transfer is often dictated by the concentration gradient of the specific lipid and the activity of enzymes that modify lipids. For example, the transfer of cholesterol from the plasma membrane to the endoplasmic reticulum (ER) is driven by the lower concentration of cholesterol in the ER and the activity of enzymes that modify cholesterol in the ER.

Intermembrane lipid transfer is critical for various cellular processes, including:

- **Membrane biogenesis:** Lipid transfer is essential for the formation and maintenance of cellular membranes, ensuring the correct lipid composition for each membrane.
- **Signal transduction:** Lipids play crucial roles in signal transduction pathways, and their transfer between membranes can regulate these pathways.
- **Organelle function:** Lipid transfer is vital for the proper function of various organelles, such as mitochondria, lysosomes, and peroxisomes, by providing the necessary lipids for their biogenesis and activity.
- **Cell growth and differentiation:** Lipid transfer is involved in regulating cell growth, differentiation, and apoptosis.

Dysregulation of intermembrane lipid transfer can lead to various diseases, including atherosclerosis, neurodegenerative disorders, and cancer. Therefore, understanding the mechanisms of intermembrane lipid transfer is crucial for developing therapeutic strategies for these diseases.
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Proteins (2)

Compounds (6)