Phospholipases

Article By:

Exton, John H. Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.900121

Enzymes that hydrolyze membrane phospholipids to generate products that are involved in the regulation of many cellular processes. The activity of phospholipases is controlled by a wide variety of agonists, including hormones, neurotransmitters, growth factors, and cytokines. The principal phospholipases are designated PLA₁, PLA₂, PLC, and PLD, and they cleave phospholipids at different sites (Fig. 1). PLA₁ releases fatty acids from the first position (F₁) of phospholipids, whereas PLA₂ cleaves them from the second position (F₂). PLC hydrolyzes phospholipids at the phosphodiester bond to produce diacylglycerol (DAG) and a phosphorylated head group, as found in phosphocholine or phosphoinositol. PLD hydrolyzes the phosphodiester bond at a different site to yield phosphatidic acid and a free head group, as found in choline or ethanolamine. Phospholipases are widely distributed in nature and are found in almost all mammalian cells. In mammals, the principal substrates of PLA₁, PLA₂, and PLD are phosphatidylcholine and phosphatidylethanolamine, whereas PLC acts on phosphatidylinositol (PI) and its mono- and bis-phosphates (PIP and PIP₂). In plants and bacteria, the phospholipases are less selective toward their substrates. See also: Enzyme; Phospholipid

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