Phospholipase C

Phospholipase C (PLC) is a class of membrane-associated enzymes that cleave phospholipids just before the phosphate group (see cleavage). It is most commonly associated with the hydrolysis of Phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG) which function as second messengers.

Function[edit | edit source]

Phospholipase C plays a crucial role in the intracellular signaling pathway. It is activated by many types of cell-surface receptors, including G protein-coupled receptors and tyrosine kinase receptors.

Upon activation, PLC cleaves PIP2 into IP3 and DAG. IP3 is released into the cytosol and binds to IP3 receptors, particularly in the endoplasmic reticulum (ER), to release calcium ions into the cytoplasm. This increase in calcium ion concentration triggers a cascade of intracellular events to carry out various cellular functions.

DAG remains in the plasma membrane and acts as a secondary messenger by activating protein kinase C (PKC). PKC then goes on to phosphorylate other proteins, leading to altered cellular activity.

Isoforms[edit | edit source]

There are thirteen known forms of mammalian phospholipase C that are categorized into six types: PLC-β, PLC-γ, PLC-δ, PLC-ε, PLC-ζ, and PLC-η. Each type has a unique structure and distribution of expression, and each plays a distinct role in cellular function.

Clinical significance[edit | edit source]

Mutations in PLC can lead to various diseases. For example, mutations in PLC-β3 and PLC-γ2 can lead to autoimmune diseases and immunodeficiency respectively.

File:Phospholipase C.png

Phospholipase C cleaving a phospholipid