PROSITE documentation PDOC00109
Phospholipase A2 active sites signatures


Phospholipase A2 (EC (PA2) [1,2] is an enzyme which releases fatty acids from the second carbon group of glycerol. PA2's are small and rigid proteins of 120 amino-acid residues that have four to seven disulfide bonds. PA2 binds a calcium ion which is required for activity. The side chains of two conserved residues, a histidine and an aspartic acid, participate in a 'catalytic network'.

Many PA2's have been sequenced from snakes, lizards, bees and mammals. In the latter, there are at least four forms: pancreatic, membrane-associated as well as two less characterized forms. The venom of most snakes contains multiple forms of PA2. Some of them are presynaptic neurotoxins which inhibit neuromuscular transmission by blocking acetylcholine release from the nerve termini.

We derived two different signature patterns for PA2's. The first is centered on the active site histidine and contains three cysteines involved in disulfide bonds. The second is centered on the active site aspartic acid and also contains three cysteines involved in disulfide bonds.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

PA2_ASP, PS00119; Phospholipase A2 aspartic acid active site  (PATTERN)

PA2_HIS, PS00118; Phospholipase A2 histidine active site  (PATTERN)


1AuthorsDavidson F.F. Dennis E.A.
TitleEvolutionary relationships and implications for the regulation of phospholipase A2 from snake venom to human secreted forms.
SourceJ. Mol. Evol. 31:228-238(1990).
PubMed ID2120459

2AuthorsGomez F. Vandermeers A. Vandermeers-Piret M.-C. Herzog R. Rathe J. Stievenart M. Winand J. Christophe J.
TitlePurification and characterization of five variants of phospholipase A2 and complete primary structure of the main phospholipase A2 variant in Heloderma suspectum (Gila monster) venom.
SourceEur. J. Biochem. 186:23-33(1989).
PubMed ID2480893

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