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Protein: CAH4_HUMAN

Carbonic anhydrase 4

FUNCTION: Reversible hydration of carbon dioxide. May stimulate the sodium/bicarbonate transporter activity of SLC4A4 that acts in pH homeostasis. It is essential for acid overload removal from the retina and retina epithelium, and acid release in the choriocapillaris in the choroid. CATALYTIC ACTIVITY: H(2)CO(3) = CO(2) + H(2)O. COFACTOR: Zinc. more...

ENZYME REGULATION: Activated by histamine, L-adrenaline, D- phenylalanine, L- and D-histidine. Inhibited by coumarins, saccharin, sulfonamide derivatives such as acetazolamide and Foscarnet (phosphonoformate trisodium salt). BIOPHYSICOCHEMICAL PROPERTIES: Kinetic parameters: KM=21.5 mM for CO(2);

SUBUNIT: Interacts with SLC4A4.

SUBCELLULAR LOCATION: Cell membrane; Lipid-anchor, GPI-anchor.

TISSUE SPECIFICITY: Expressed in the endothelium of the choriocapillaris in eyes (at protein level). Not expressed in the retinal epithelium at detectable levels.

DISEASE: Defects in CA4 are the cause of retinitis pigmentosa type 17 (RP17) [MIM:600852]. RP leads to degeneration of retinal photoreceptor cells. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well. RP17 inheritance is autosomal dominant. Note=Defective acid overload removal from retina and retinal epithelium, due to mutant CA4, is responsible for photoreceptor degeneration, indicating that impaired pH homeostasis is the most likely cause underlying the RP17 phenotype.

SIMILARITY: Belongs to the alpha-carbonic anhydrase family.

COPYRIGHT: Protein annotation is derived from the UniProt Consortium (http://www.uniprot.org/). Distributed under the Creative Commons Attribution-NoDerivs License.

 

Organism:

  • Homo sapiens

Gene Symbol:

  • CA4

Synonyms:

  • CA-IV
  • 4.2.1.1
  • Carbonate dehydratase IV
  • Carbonic anhydrase IV

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