Pathways & interactions
Alpha carbonic anhydrase domain superfamily (IPR036398)
Short name: CA_dom_sf
- Alpha carbonic anhydrase domain (IPR001148)
- Carbonic anhydrase, CA4 (IPR018343)
- Putative carbonic anhydrase-like protein 2 (IPR018347)
- Carbonic anhydrase-related protein 10 (IPR018423)
- Carbonic anhydrase, CA15 (IPR018426)
- Carbonic anhydrase, CA-VI (IPR018428)
- Carbonic anhydrase 9 (IPR018429)
- Carbonic anhydrase, CA-XII (IPR018430)
- Carbonic anhydrase, CA14 (IPR018431)
- Carbonic anhydrase VB, mitochondria (IPR018437)
- Carbonic anhydrase, CA3 (IPR018441)
- Carbonic anhydrase, CA1 (IPR018442)
- Carbonic anhydrase, alpha-class (IPR023561)
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 [PMID: 9336012]. 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 [PMID: 8673298, PMID: 11493685].
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 [PMID: 8382771].
Carbonic anhydrases (CA: EC:126.96.36.199) are zinc metalloenzymes which catalyse the reversible hydration of carbon dioxide to bicarbonate [PMID: 18336305, PMID: 10978542]. 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).