leukotriene receptor activity

Definition

Target type: molecularfunction

Combining with a leukotriene to initiate a change in cell activity. Leukotrienes are pharmacologically active substances with a set of three conjugated double bonds; some contain a peptide group based on cysteine. [GOC:ai, ISBN:0198506732]

Leukotriene receptors are G protein-coupled receptors (GPCRs) that mediate the cellular responses to leukotrienes, a class of lipid mediators involved in inflammation, allergic reactions, and other physiological processes. Leukotrienes are produced from arachidonic acid through the action of the enzyme 5-lipoxygenase. They bind to and activate specific receptors, leading to downstream signaling cascades that ultimately regulate various cellular functions.

Leukotriene receptors are classified into two main subtypes:

* **CysLT receptors:** These receptors bind to cysteinyl leukotrienes (LTC4, LTD4, and LTE4) and are primarily involved in mediating the bronchoconstriction, mucus secretion, and vascular permeability associated with asthma and other allergic diseases.
* **BLT receptors:** These receptors bind to leukotriene B4 (LTB4) and play a role in the recruitment and activation of leukocytes, particularly neutrophils, to sites of inflammation.

The molecular function of leukotriene receptor activity can be described in the following steps:

1. **Ligand binding:** Leukotrienes bind to their specific receptors, initiating a conformational change in the receptor protein.
2. **G protein activation:** The activated receptor interacts with a heterotrimeric G protein, leading to the exchange of GDP for GTP on the alpha subunit of the G protein.
3. **Second messenger production:** The activated alpha subunit of the G protein activates downstream signaling pathways, often involving the production of second messengers such as inositol trisphosphate (IP3) and diacylglycerol (DAG).
4. **Cellular response:** The increased levels of second messengers trigger a variety of cellular responses, including:
* **Smooth muscle contraction:** This is particularly relevant in the bronchi, where leukotrienes contribute to airway narrowing.
* **Vascular permeability:** Leukotrienes can increase the leakage of fluid from blood vessels, contributing to edema and tissue swelling.
* **Leukocyte recruitment:** Leukotriene B4, through its interaction with BLT receptors, attracts and activates neutrophils, which play a crucial role in the inflammatory response.
* **Cellular proliferation:** Leukotrienes can also influence cell growth and differentiation.

Leukotriene receptor activity is essential for mediating the physiological effects of leukotrienes, but it can also contribute to pathological conditions. For example, excessive leukotriene production and signaling are implicated in the development and progression of asthma, allergic rhinitis, and other inflammatory diseases. Therefore, leukotriene receptor antagonists, which block the binding of leukotrienes to their receptors, have become important therapeutic agents for the treatment of these conditions.'
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Proteins (4)

Compounds (60)