InterPro domain: IPR036398

General Information

  • Identifier IPR036398
  • Description Alpha carbonic anhydrase domain superfamily
  • Number of genes 997
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Abstract

This entry represents a domain characteristic of alpha class carbonic anhydrases. The dominating secondary structure is a 10-stranded, twisted beta-sheet, which divides the molecules into two halves [ 1 ]. Alpha-CAs contain a single zinc atom bound to three conserved histidine residues. The catalytically active group is the zinc-bound water which ionizes to a hydroxide group. In the mechanism of catalysis, nucleophilic attack of CO2 by a zinc-bound hydroxide ion is followed by displacement of the resulting zinc-bound bicarbonate ion by water; subsequent deprotonation regenerates the nucleophilic zinc-bound hydroxide ion [ 2 , 3 ].

A carbonic anhydrase-like domain with striking homology to that of the alpha class carbonic anhydrases is also found in receptor-type tyrosine-protein phosphatase gamma and zeta. In this case it may have a different function, as only one of the three His residues that ligate the zinc atom and are required for catalytic activity is conserved [ 4 ].

Carbonic anhydrases (CA: 4.2.1.1 ) are zinc metalloenzymes which catalyse the reversible hydration of carbon dioxide to bicarbonate [ 5 , 6 ]. The alpha-CAs are found predominantly in animals but also in bacteria and green algae. There are at least 15 isoforms found in mammals, which can be subdivided into cytosolic CAs (CA-I, CA-II, CA-III, CA-VII and CA XIII), mitochondrial CAs (CA-VA and CA-VB), secreted CAs (CA-VI), membrane-associated (CA-IV, CA-IX, CA-XII and CA-XIV) and those without CA activity, the CA-related proteins (CA-RP VIII, X and XI).


1. Structure and mechanism of carbonic anhydrase. Pharmacol. Ther. 74, 1-20
2. Functional diversity, conservation, and convergence in the evolution of the alpha-, beta-, and gamma-carbonic anhydrase gene families. Mol. Phylogenet. Evol. 5, 50-77
3. Crystal structure of the dimeric extracellular domain of human carbonic anhydrase XII, a bitopic membrane protein overexpressed in certain cancer tumor cells. Proc. Natl. Acad. Sci. U.S.A. 98, 9545-50
4. Identification of a carbonic anhydrase-like domain in the extracellular region of RPTP gamma defines a new subfamily of receptor tyrosine phosphatases. Mol. Cell. Biol. 13, 1497-506
5. Carbonic anhydrases--an overview. Curr. Pharm. Des. 14, 603-14
6. Prokaryotic carbonic anhydrases. FEMS Microbiol. Rev. 24, 335-66

Species distribution

Gene table

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