A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. Acids trigger the release of bound calcium from cellular stores and the consequent increase in free cytosolic Ca2+, an essential step in calcium signaling to regulate intracellular processes. There are four major classes, termed A, B, C, and D, which are distinguished by the type of reaction which they catalyze:
- Phospholipase A
- Phospholipase A1 – cleaves the sn-1 acyl chain (where sn refers to stereospecific numbering).
- Phospholipase A2 – cleaves the sn-2 acyl chain, releasing arachidonic acid.
- Phospholipase B – cleaves both sn-1 and sn-2 acyl chains; this enzyme is also known as a lysophospholipase.
- Phospholipase C – cleaves before the phosphate, releasing diacylglycerol and a phosphate-containing head group. PLCs play a central role in signal transduction, releasing the second messenger inositol triphosphate.
- Phospholipase D – cleaves after the phosphate, releasing phosphatidic acid and an alcohol.
Types C and D are considered phosphodiesterases.
Endothelial lipase is primarily a phospholipase.
Phospholipase A2 acts on the intact lecithin molecule and hydrolyzes the fatty acid esterified to the second carbon atom. The resulting products are lysolecithin and a fatty acid. Phospholipase A2 is an enzyme present in the venom of bees, blennies and viper snakes.
- ^ "phospholipase" at Dorland's Medical Dictionary
- ^ Molinari, Giuliano; Nervo, Elsa (2021-02-26). "Role of protons in calcium signaling". The Biochemical Journal. 478 (4): 895–910. doi:10.1042/BCJ20200971. ISSN 1470-8728. PMID 33635336.
- ^ Yu JE, Han SY, Wolfson B, Zhou Q (2018). "The role of endothelial lipase in lipid metabolism, inflammation, and cancer". Histology and Histopathology. 33 (1): 1–10. doi:10.14670/HH-11-905. PMC 5858721. PMID 28540715.
- ^ D. M. Vasudevan & S. Sreekumari, Textbook of Biochemistry (5th ed.)
- Tappia, Paramjit S. & Dhalla, Naranjan S. (Editors): Phospholipases in Health and Disease. Springer, 2014. ISBN 978-1-4939-0463-1 [Print]; ISBN 978-1-4939-0464-8 [eBook]
- Phospholipases at the US National Library of Medicine Medical Subject Headings (MeSH)