low-density lipoprotein particle binding

Definition

Target type: molecularfunction

Binding to a low-density lipoprotein particle, a lipoprotein particle that is rich in cholesterol esters and low in triglycerides, is typically composed of APOB100 and APOE, and has a density of 1.02-1.06 g/ml and a diameter of between 20-25 nm. [GOC:mah]

Low-density lipoprotein (LDL) particles, also known as "bad cholesterol", are crucial for delivering cholesterol to cells throughout the body. The molecular function of LDL particle binding involves a complex interplay of proteins and lipids that facilitate this delivery process.

1. **Ligand Recognition:** LDL particles possess a unique structure with a core of cholesterol esters surrounded by a monolayer of phospholipids and apolipoprotein B-100 (apoB-100). ApoB-100 serves as the primary ligand that binds to LDL receptors (LDLR) on the surface of cells. The interaction between apoB-100 and LDLR is highly specific and mediated by a series of amino acid residues on both molecules.

2. **Receptor-mediated Endocytosis:** Once the LDL particle binds to the LDLR, the complex is internalized into the cell via endocytosis. This process is initiated by the clustering of LDLRs and the formation of clathrin-coated pits, which invaginate and pinch off from the plasma membrane.

3. **Uncoating and Trafficking:** The clathrin-coated vesicle containing the LDL particle undergoes uncoating, releasing the LDL into an early endosome. The endosome then acidifies, causing a conformational change in the LDLR, which weakens its hold on the LDL particle.

4. **Lysosomal Degradation:** The LDL particle is transported to a late endosome, which eventually fuses with a lysosome. The acidic environment and the presence of lysosomal hydrolases within the lysosome break down the LDL particle, releasing free cholesterol into the cytoplasm.

5. **Cholesterol Utilization:** The cholesterol liberated from LDL particles is used by the cell for various purposes, including the synthesis of hormones, cell membranes, and bile acids.

6. **LDLR Recycling:** The LDLR, after releasing the LDL particle, is recycled back to the cell surface, ready to bind another LDL particle. This recycling process ensures continuous uptake of LDL cholesterol.

In summary, the molecular function of LDL particle binding involves a series of tightly regulated events, from ligand recognition and receptor-mediated endocytosis to lysosomal degradation and cholesterol utilization. This process is crucial for maintaining cholesterol homeostasis in the body and preventing the development of cardiovascular disease.'
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Proteins (4)

Compounds (5)