high-density lipoprotein particle receptor activity

Definition

Target type: molecularfunction

Combining with a high-density lipoprotein particle and delivering the high-density lipoprotein into the cell via endocytosis. [GOC:bf, GOC:BHF, GOC:rl, PMID:9211901]

High-density lipoprotein (HDL) particle receptor activity is a crucial process in lipid metabolism and cholesterol homeostasis. HDL receptors, primarily scavenger receptor class B type I (SR-BI) and the ATP-binding cassette transporter A1 (ABCA1), mediate the selective uptake of cholesterol esters from HDL particles into cells. This process is essential for maintaining cellular cholesterol levels and preventing the accumulation of cholesterol in the bloodstream, which can lead to atherosclerosis and cardiovascular disease.

The molecular function of HDL particle receptor activity involves a complex interplay of protein-protein interactions, lipid binding, and intracellular signaling pathways.

1. **Binding of HDL to the Receptor:** HDL particles bind to the receptor, typically through a specific recognition site on the receptor protein. This binding event is often facilitated by the presence of apolipoproteins, particularly apolipoprotein A-I (ApoA-I), on the surface of HDL particles.

2. **Internalization of HDL:** After binding, the receptor-HDL complex is internalized into the cell through endocytosis. This process involves the invagination of the cell membrane, forming a vesicle that encapsulates the HDL particle.

3. **Cholesterol Ester Transfer:** Once inside the cell, the HDL particle undergoes a process called selective uptake. This involves the transfer of cholesterol esters from the HDL particle to the cell's intracellular lipid stores. The transfer process is mediated by the specific structure of the receptor, which allows for the selective movement of cholesterol esters without the uptake of the entire HDL particle.

4. **Recycling of HDL:** The remaining HDL particle, depleted of cholesterol esters, is typically recycled back into the bloodstream. This recycling step ensures the efficient utilization of HDL particles and promotes the continued removal of cholesterol from peripheral tissues.

5. **Intracellular Signaling:** The interaction of HDL with its receptor can also activate intracellular signaling pathways. These pathways can influence cellular processes related to cholesterol metabolism, inflammation, and cell survival.

In summary, high-density lipoprotein particle receptor activity plays a vital role in maintaining cholesterol homeostasis by facilitating the selective uptake of cholesterol esters from HDL particles, thereby reducing cholesterol levels in the bloodstream and protecting against cardiovascular disease. The process involves the binding of HDL to receptors, internalization, cholesterol ester transfer, recycling, and the activation of intracellular signaling pathways.'
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Proteins (1)

Compounds (1)