activation of phospholipase C activity

Definition

Target type: biologicalprocess

The initiation of the activity of the inactive enzyme phospolipase C as the result of The series of molecular signals generated as a consequence of a G protein-coupled receptor binding to its physiological ligand. [GOC:dph, GOC:mah, GOC:tb, PMID:8280098]

Phospholipase C (PLC) is an enzyme that catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into diacylglycerol (DAG) and inositol trisphosphate (IP3). This hydrolysis reaction is a crucial step in many signaling pathways, particularly those involving G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs).

The activation of PLC activity involves a complex interplay of signaling molecules and events. Here's a detailed breakdown:

1. **Receptor Activation:** The process begins with the binding of a ligand to its specific receptor, either a GPCR or an RTK. This binding event triggers a conformational change in the receptor, initiating a signaling cascade.

2. **G Protein Activation (for GPCRs):** In the case of GPCRs, the activated receptor interacts with a heterotrimeric G protein, composed of alpha, beta, and gamma subunits. This interaction causes the alpha subunit to dissociate from the beta-gamma dimer, exchanging GDP for GTP. The activated alpha subunit, carrying GTP, then interacts with and activates PLC.

3. **Tyrosine Kinase Activation (for RTKs):** For RTKs, ligand binding induces dimerization of the receptor, leading to autophosphorylation of tyrosine residues within the intracellular domain. These phosphorylated tyrosines serve as docking sites for adapter proteins, which in turn activate PLC.

4. **PLC Activation:** Both activated G proteins and adapter proteins associated with RTKs bind to and activate PLC. PLC isoforms differ in their specific mechanisms of activation and downstream signaling.

5. **PIP2 Hydrolysis:** Activated PLC catalyzes the hydrolysis of PIP2, a phospholipid located in the inner leaflet of the plasma membrane. This hydrolysis reaction results in the production of two second messengers: DAG and IP3.

6. **Second Messenger Signaling:** DAG remains associated with the plasma membrane, where it activates protein kinase C (PKC), a key regulator of various cellular processes. IP3 diffuses into the cytosol and binds to IP3 receptors on the endoplasmic reticulum (ER). This binding triggers the release of calcium ions (Ca2+) from the ER, leading to a rise in intracellular calcium levels.

7. **Cellular Responses:** The downstream signaling triggered by DAG, IP3, and calcium ions results in a wide array of cellular responses, including:
* **Cell proliferation and differentiation**
* **Muscle contraction**
* **Neurotransmitter release**
* **Gene expression**
* **Apoptosis**

In summary, the activation of PLC activity is a highly regulated process that involves the coordinated action of receptors, G proteins, adapter proteins, and enzymes. The resulting production of DAG and IP3 initiates complex signaling cascades that influence a wide range of cellular functions.'
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Proteins (16)

Compounds (931)