CA2 - Carbonic anhydrase 2 - human protein (Function)
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CA2 »  Carbonic anhydrase 2   [ EC ]
Protein also known as:  Carbonate dehydratase II.
Gene name:  CA2
Entry whose protein(s) existence is based on evidence at protein level
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Essential for bone resorption and osteoclast differentiation (By similarity). Reversible hydration of carbon dioxide. Can hydrate cyanamide to urea. Involved in the regulation of fluid secretion into the anterior chamber of the eye. Contributes to intracellular pH regulation in the duodenal upper villous epithelium during proton-coupled peptide absorption. Stimulates the chloride-bicarbonate exchange activity of SLC26A6.  
  • CuratedUniProtKB
GO molecular function 
Carbonate dehydratase activitydefinition[GO:0004089]  
  • IEAEC 2 GO
Protein bindingdefinition[GO:0005515]  
  • IPIUniProtKB
Zinc ion bindingdefinition[GO:0008270]  
  • IDAUniProtKB
GO biological process 
Angiotensin-activated signaling pathwaydefinition[GO:0038166]  
  • IDAUniProtKB
Carbon dioxide transportdefinition[GO:0015670] silver  
  • IEAOrtholog Compara
Kidney developmentdefinition[GO:0001822] silver  
  • IEAOrtholog Compara
Morphogenesis of an epitheliumdefinition[GO:0002009] silver  
  • IEAOrtholog Compara
Odontogenesis of dentin-containing toothdefinition[GO:0042475] silver  
  • IEAOrtholog Compara
One-carbon metabolic processdefinition[GO:0006730] silver  
  • IEAInterPro 2 GO
Positive regulation of bone resorptiondefinition[GO:0045780] silver  
  • IEAOrtholog Compara
Positive regulation of cellular pH reductiondefinition[GO:0032849] silver  
  • IEAOrtholog Compara
Positive regulation of dipeptide transmembrane transportdefinition[GO:2001150]  
  • ISSOrtholog Curator
Positive regulation of osteoclast differentiationdefinition[GO:0045672] silver  
  • IEAOrtholog Compara
Regulation of anion transportdefinition[GO:0044070]  
  • IDAUniProtKB
Regulation of intracellular pHdefinition[GO:0051453]  
  • ISSOrtholog Curator
Response to estrogendefinition[GO:0043627] silver  
  • IEAOrtholog Compara
Response to pHdefinition[GO:0009268] silver  
  • IEAOrtholog Compara
Response to zinc iondefinition[GO:0010043] silver  
  • IEAOrtholog Compara
Secretiondefinition[GO:0046903] silver  
  • IEAOrtholog Compara
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC H(2)CO(3) CO(2) + H(2)O.  
  • CuratedUniProtKB
It requires the following cofactor
Zinc. Can also use cobalt(II) with lower efficiency, but not copper(II), nickel(II) and manganese(II).  
  • CuratedUniProtKB
It is regulated in the following manner
Activated by X-ray, histamine, L-adrenaline, L- and D-phenylalanine, L- and D-histidine, L-His-OMe and beta-Ala-His (carnosine). Competitively inhibited by saccharin, thioxolone, coumarins, 667-coumate, celecoxib (Celebrex), valdecoxib (Bextra), SC-125, SC-560, diclofenac, acetate, azide, bromide, sulfonamide derivatives such as acetazolamide (AZA), methazolamide (MZA), ethoxzolamide (EZA), dichlorophenamide (DCP), brinzolamide, dansylamide, thiabendazole-5-sulfonamide, trifluoromethane sulfonamide and N-hydroxysulfamide, fructose-based sugar sulfamate RWJ-37497, and Foscarnet (phosphonoformate trisodium salt). Repressed strongly by hydrogen sulfide(HS) and weakly by nitrate (NO(3)). Esterase activity weakly reduced by cyanamide. N-hydroxyurea interfers with zinc binding and inhibit activity.  
  • CuratedUniProtKB
More information is available from:
According to KEGG, this protein belongs to the following pathways:
Bile secretion  hsa04976+760  
Collecting duct acid secretion  hsa04966+760  
Gastric acid secretion  hsa04971+760  
Nitrogen metabolism  hsa00910+760  
Pancreatic secretion  hsa04972+760  
Proximal tubule bicarbonate reclamation  hsa04964+760  
According to Reactome, this protein belongs to the following pathways:
Erythrocytes take up carbon dioxide and release oxygen  REACT_121329  
Erythrocytes take up oxygen and release carbon dioxide  REACT_121380  
Reversible hydration of carbon dioxide  REACT_121123  
Target of drugs used in treatments against glaucoma disorder and breast cancer.  
  • CuratedUniProtKB

Biophysicochemical properties

Abs(max) 550 nm
At pH 7.0. Shows a second maximum at 618 nm.
Kinetic parameters
KM 10 mM for CO(2)
KM 82 mM for H(2)CO(3)
KM 3 mM for 4-nitrophenyl acetate
pH Optimum pH is 6-8.


Molecular function 
Lyase  definition   [KW-0456]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

Enzyme and pathway databases
SABIO-RK: P00918
GeneWiki: Carbonic_anhydrase_II
GenomeRNAi: 760
PRO: PR:P00918