UniProt functional annotation for P22748

UniProt code: P22748.

Organism: Homo sapiens (Human).
Taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.
 
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. {ECO:0000269|PubMed:15563508}.
 
Catalytic activity: H(2)CO(3) = CO(2) + H(2)O.
Cofactor: Zinc.
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). {ECO:0000269|PubMed:16686544, ECO:0000269|PubMed:16807956, ECO:0000269|PubMed:17127057, ECO:0000269|PubMed:17314045, ECO:0000269|PubMed:17705204, ECO:0000269|PubMed:18618712, ECO:0000269|PubMed:19186056, ECO:0000269|PubMed:19206230}.
Biophysicochemical properties: Kinetic parameters: KM=21.5 mM for CO(2) {ECO:0000269|PubMed:18618712};
Subunit: Interacts with SLC4A4. {ECO:0000269|PubMed:15563508, ECO:0000269|PubMed:17652713, ECO:0000269|PubMed:20363633, ECO:0000269|PubMed:8942978}.
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. {ECO:0000269|PubMed:15563508}.
Disease: Retinitis pigmentosa 17 (RP17) [MIM:600852]: A retinal dystrophy belonging to the group of pigmentary retinopathies. Retinitis pigmentosa is characterized by retinal pigment deposits visible on fundus examination and primary loss of rod photoreceptor cells followed by secondary loss of cone photoreceptors. 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. {ECO:0000269|PubMed:15563508, ECO:0000269|PubMed:17652713, ECO:0000269|PubMed:20450258}. Note=The disease is caused by mutations affecting the gene represented in this entry. 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. {ECO:0000305}.

Annotations taken from UniProtKB at the EBI.