lipopolysaccharide immune receptor activity

Definition

Target type: molecularfunction

Combining with a lipopolysaccharide and transmitting the signal across the cell membrane to initiate an innate immune response. Lipopolysaccharides (LPS) are major components of the outer membrane of Gram-negative bacteria, making them prime targets for recognition by the immune system. [PMID:14609719, PMID:15379975]

Lipopolysaccharide (LPS) immune receptor activity is a crucial component of the innate immune response, primarily mediated by Toll-like receptor 4 (TLR4). LPS, a major component of the outer membrane of Gram-negative bacteria, triggers a cascade of signaling events upon binding to TLR4. This interaction leads to the activation of downstream signaling pathways, such as the NF-κB pathway, ultimately resulting in the production of pro-inflammatory cytokines and the initiation of immune responses.

The molecular function of LPS immune receptor activity encompasses several key steps:

1. **LPS recognition:** TLR4, in conjunction with its co-receptors MD-2 and CD14, specifically recognizes and binds to LPS. The interaction between TLR4 and LPS is facilitated by the formation of a complex involving LPS, MD-2, and TLR4, enabling signal transduction.

2. **Signal transduction:** Upon LPS binding, TLR4 undergoes a conformational change, leading to the recruitment of adaptor proteins, such as MyD88 and TRIF, to the intracellular domain of TLR4. These adaptor proteins initiate distinct signaling cascades.

3. **Activation of downstream signaling pathways:** MyD88 activates the NF-κB pathway, while TRIF activates both the NF-κB pathway and the interferon regulatory factor 3 (IRF3) pathway. These pathways regulate the expression of various genes involved in immune responses.

4. **Cytokine production:** Activated NF-κB and IRF3 pathways stimulate the transcription and translation of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), and interleukin-6 (IL-6). These cytokines mediate various immune responses, including inflammation, fever, and leukocyte recruitment.

5. **Immune response activation:** The production of pro-inflammatory cytokines and the activation of immune cells, such as macrophages and neutrophils, contribute to the initiation and amplification of the innate immune response against bacterial infections.

The intricate molecular function of LPS immune receptor activity highlights the critical role of TLR4 in sensing microbial threats and initiating appropriate immune responses. This activity is essential for host defense against Gram-negative bacterial infections and plays a significant role in the development and regulation of both innate and adaptive immune responses.'
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Proteins (5)

Compounds (47)