Protein Domain : IPR023561

Type:  Family Name:  Carbonic anhydrase, alpha-class
Description:  Carbonic anhydrases (CA: ) are zinc metalloenzymes which catalyse the reversible hydration of carbon dioxide to bicarbonate [, ]. CAs have essential roles in facilitating the transport of carbon dioxide and protons in the intracellular space, across biological membranes and in the layers of the extracellular space; they are also involved in many other processes, from respiration and photosynthesis in eukaryotes to cyanate degradation in prokaryotes. There are five known evolutionarily distinct CA families (alpha, beta, gamma, delta and epsilon) that have no significant sequence identity and have structurally distinct overall folds. Some CAs are membrane-bound, while others act in the cytosol; there are several related proteins that lack enzymatic activity. The active site of alpha-CAs is well described, consisting of a zinc ion coordinated through 3 histidine residues and a water molecule/hydroxide ion that acts as a potent nucleophile. The enzyme employs a two-step mechanism: in the first step, there is a nucleophilic attack of a zinc-bound hydroxide ion on carbon dioxide; in the second step, the active site is regenerated by the ionisation of the zinc-bound water molecule and the removal of a proton from the active site []. Beta- and gamma-CAs also employ a zinc hydroxide mechanism, although at least some beta-class enzymes do not have water directly coordinated to the metal ion. 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).The beta-CAs are highly abundant in plants, diatoms, eubacteria and archaea [, ]. The beta-CAs are far more diverse in sequence than other classes, and can be divided into different clades based on sequence identity, with the plant enzymes forming two clades representing dicotyledonous and monocotyledonous plants. Characterisation of these enzymes reveals sharp differences between the beta class, which forms dimers, tetramers, hexamers and octomers, and the alpha and gamma classes, which form strictly monomers and trimers. The gamma-CAs may be the most ancient form of carbonic anhydrases, having evolved long before the alpha class, to which it is more closely related than to the beta-class [, ]. The reaction mechanism of the gamma-class is similar to that of the alpha-class, even though the overall folds are dissimilar and the active site residues differ. The delta-CAs are found in marine algae and dinoflagellates []. The epsilon-CAs are found in prokaryotes such as Thiobacillus neapolitanus(Halothiobacillus neapolitanus) in which it is a component of the carboxysome shell, where it could supply the active sites of RuBisCO in the carboxysome with the high concentrations of carbon dioxide necessary for optimal RuBisCO activity and efficient carbon fixation [].This entry represents alpha class carbonic anhydrases. Short Name:  Carbonic_anhydrase_a-class
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15 Child Features

DB identifier Type Name
IPR018343 Family Carbonic anhydrase, CA4
IPR018347 Family Putative carbonic anhydrase-like protein 2
IPR018442 Family Carbonic anhydrase, CA1
IPR018443 Family Carbonic anhydrase 2
IPR018441 Family Carbonic anhydrase, CA3
IPR018428 Family Carbonic anhydrase, CA-VI
IPR018429 Family Carbonic anhydrase 9
IPR018426 Family Carbonic anhydrase, CA15
IPR018423 Family Carbonic anhydrase-related protein 10
IPR018431 Family Carbonic anhydrase, CA14
IPR018430 Family Carbonic anhydrase, CA-XII
IPR018437 Family Carbonic anhydrase VB, mitochondria
IPR018438 Family Carbonic anhydrase, CA-VII
IPR018433 Family Carbonic anhydrase, putative, insect
IPR018434 Family Carbonic anhydrase-related protein, CA8

0 Contains

1 Cross References

Identifier
PTHR18952

0 Found In

0 GO Annotation

0 Ontology Annotations

0 Parent Features

3256 Proteins

DB identifier UniProt Accession Secondary Identifier Organism Name Length
93576 D8RGH6 PAC:15422036 Selaginella moellendorffii 235  
411805 D8RJ34 PAC:15411618 Selaginella moellendorffii 242  
412164 D8RK96 PAC:15409291 Selaginella moellendorffii 554  
77903 D8QUE6 PAC:15422253 Selaginella moellendorffii 232  
416362 D8RZ19 PAC:15422427 Selaginella moellendorffii 258  
105891 D8S0N7 PAC:15418072 Selaginella moellendorffii 207  
105754 D8S0N8 PAC:15417221 Selaginella moellendorffii 82  
106066 D8S113 PAC:15414908 Selaginella moellendorffii 198  
108874 D8S528 PAC:15404383 Selaginella moellendorffii 245  
113076 D8SBP0 PAC:15413331 Selaginella moellendorffii 238  
420338 D8SBP1 PAC:15412105 Selaginella moellendorffii 289  
420339 D8SBP2 PAC:15412106 Selaginella moellendorffii 160  
420354 D8SBQ8 PAC:15412154 Selaginella moellendorffii 270  
407267 D8R4G9 PAC:15417476 Selaginella moellendorffii 586  
36096 D8QRS8 PAC:15406264 Selaginella moellendorffii 130  
159358 D8SY70 PAC:15417203 Selaginella moellendorffii 251  
133933 D8T807 PAC:15412140 Selaginella moellendorffii 111  
429368 D8T5Y8 PAC:15416188 Selaginella moellendorffii 179  
133488 D8T703 PAC:15408345 Selaginella moellendorffii 233  
429383 D8T605 PAC:15416227 Selaginella moellendorffii 188  
132930 D8T606 PAC:15409202 Selaginella moellendorffii 97  
evm.model.supercontig_182.21 PAC:16411572 Carica papaya 263  
evm.model.supercontig_182.22 PAC:16411573 Carica papaya 244  
evm.model.supercontig_182.23 PAC:16411574 Carica papaya 248  
evm.model.supercontig_311.9 PAC:16417265 Carica papaya 174  
evm.model.supercontig_311.11 PAC:16417257 Carica papaya 129  
evm.model.supercontig_5.13 PAC:16421229 Carica papaya 251  
evm.model.supercontig_92.97 PAC:16428672 Carica papaya 291  
30078.m002256 B9S0D9 PAC:16817367 Ricinus communis 274  
44217.m000025 B9TND7 PAC:16827672 Ricinus communis 185  

9 Publications

First Author Title Year Journal Volume Pages PubMed ID
            14729686
            9336012
            18336305
            10978542
            16407248
            12107142
            18289884
            18336318
            18467453