receptor-mediated endocytosis involved in cholesterol transport

Definition

Target type: biologicalprocess

A receptor-mediated endocytosis process involved in intracellular cholesterol transport. [GOC:ascb_2009, GOC:dph, GOC:pr, GOC:tb]

Receptor-mediated endocytosis (RME) is a crucial process for cholesterol transport, enabling cells to internalize and utilize cholesterol from extracellular sources. This intricate process involves a series of coordinated steps:

1. **Ligand Binding:** Cholesterol, bound to lipoproteins like low-density lipoprotein (LDL), interacts with specific receptors on the cell surface. These receptors, primarily LDL receptors (LDLRs), are transmembrane proteins with a binding domain for LDL particles.
2. **Clathrin-Coated Pit Formation:** Once LDL binds to LDLRs, the receptor-ligand complex initiates the formation of clathrin-coated pits (CCPs) on the plasma membrane. Clathrin, a protein that forms a cage-like structure, assembles around the receptors, creating a localized invagination.
3. **Vesicle Budding:** As the CCP grows, it pinches off from the plasma membrane, forming a small, spherical vesicle known as a clathrin-coated vesicle (CCV). This vesicle encapsulates the LDLR-LDL complex, internalizing it within the cell.
4. **Uncoating and Trafficking:** Once inside the cell, the CCV sheds its clathrin coat. The uncoated vesicle then travels to the early endosome, a sorting station within the cell.
5. **LDL Dissociation and Receptor Recycling:** Within the acidic environment of the early endosome, the LDL particles dissociate from the LDLRs. This release of LDL allows the cholesterol to be delivered to the cell's interior, while the LDLRs are recycled back to the cell surface via a trans-Golgi network pathway.
6. **Lysosomal Degradation:** The LDL particles, now freed from the LDLRs, move to the late endosome and eventually to lysosomes, where they are broken down into their constituent components. Cholesterol is then released and made available for cellular processes, such as membrane synthesis and hormone production.

This highly regulated process ensures efficient cholesterol uptake and utilization, preventing cholesterol buildup in the bloodstream and maintaining lipid homeostasis.'
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Proteins (1)

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