calcium-dependent phospholipase C activity

Definition

Target type: molecularfunction

Catalysis of the reaction: a phosphatidylcholine + H2O = 1,2-diacylglycerol + choline phosphate. This reaction requires Ca2+. [PMID:25769297, PMID:9426125]

Calcium-dependent phospholipase C (PLC) activity is a crucial enzymatic process involved in the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into two second messengers: diacylglycerol (DAG) and inositol trisphosphate (IP3). This hydrolysis is catalyzed by a family of PLC enzymes that are activated by calcium ions. The molecular function of calcium-dependent PLC activity can be summarized in the following steps:

1. **Calcium Binding:** Calcium ions bind to specific sites on the PLC enzyme, inducing a conformational change that activates the enzyme. This calcium-dependent activation is essential for regulating the activity of PLC.
2. **PIP2 Binding:** The activated PLC enzyme binds to PIP2, a phospholipid found in the inner leaflet of the plasma membrane.
3. **Hydrolysis:** PLC cleaves the phosphodiester bond between the phosphate group at position 4 and the inositol ring of PIP2. This hydrolysis reaction generates two important signaling molecules:
- **Diacylglycerol (DAG):** DAG remains in the membrane and activates protein kinase C (PKC), which phosphorylates various target proteins involved in cell growth, proliferation, and survival.
- **Inositol Trisphosphate (IP3):** IP3 diffuses into the cytoplasm and binds to IP3 receptors on the endoplasmic reticulum (ER) membrane. This binding triggers the release of calcium ions from the ER, leading to a rise in intracellular calcium concentration.
4. **Signal Transduction:** The increased calcium concentration, along with DAG, activates downstream signaling pathways, leading to various cellular responses, including:
- **Muscle contraction:** In muscle cells, calcium release via IP3 receptors triggers muscle contraction.
- **Cell growth and proliferation:** PLC activity contributes to cell growth and proliferation through the activation of PKC and other downstream targets.
- **Neurotransmitter release:** In neurons, PLC activity plays a role in neurotransmitter release by regulating the influx of calcium ions.
- **Immune responses:** PLC activity is involved in various aspects of immune responses, including the activation of immune cells and the production of inflammatory mediators.

In summary, calcium-dependent phospholipase C activity is a key enzyme in signal transduction pathways, orchestrating cellular responses by generating second messengers and regulating calcium signaling. Its diverse roles in cell growth, muscle contraction, neurotransmission, and immune responses underscore its importance in various physiological processes.'
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Proteins (2)

Compounds (5)