ID:CAH4_HUMAN DESCRIPTION: RecName: Full=Carbonic anhydrase 4; EC=4.2.1.1; AltName: Full=Carbonate dehydratase IV; AltName: Full=Carbonic anhydrase IV; Short=CA-IV; Flags: Precursor; 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. 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.
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on P22748
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
BC057792 - Homo sapiens carbonic anhydrase IV, mRNA (cDNA clone MGC:71638 IMAGE:30331755), complete cds. LP895344 - Sequence 208 from Patent EP3253886. AK289715 - Homo sapiens cDNA FLJ76600 complete cds, highly similar to Homo sapiens carbonic anhydrase IV (CA4), mRNA. AK298710 - Homo sapiens cDNA FLJ52015 complete cds, moderately similar to Carbonic anhydrase 4 precursor (EC 4.2.1.1). BC069649 - Homo sapiens carbonic anhydrase IV, mRNA (cDNA clone MGC:97195 IMAGE:7262441), complete cds. M83670 - Human carbonic anhydrase IV mRNA, complete cds. JD339335 - Sequence 320359 from Patent EP1572962. BC074768 - Homo sapiens carbonic anhydrase IV, mRNA (cDNA clone MGC:103808 IMAGE:30915189), complete cds. CU691238 - Synthetic construct Homo sapiens gateway clone IMAGE:100020823 5' read CA4 mRNA. HQ448032 - Synthetic construct Homo sapiens clone IMAGE:100071407; CCSB010783_02 carbonic anhydrase IV (CA4) gene, encodes complete protein. KJ890805 - Synthetic construct Homo sapiens clone ccsbBroadEn_00199 CA4 gene, encodes complete protein. KR710960 - Synthetic construct Homo sapiens clone CCSBHm_00018393 CA4 (CA4) mRNA, encodes complete protein. KR710961 - Synthetic construct Homo sapiens clone CCSBHm_00018394 CA4 (CA4) mRNA, encodes complete protein. KR710962 - Synthetic construct Homo sapiens clone CCSBHm_00018395 CA4 (CA4) mRNA, encodes complete protein. CR541766 - Homo sapiens full open reading frame cDNA clone RZPDo834A0430D for gene CA4, carbonic anhydrase IV; complete cds, incl. stopcodon. JD194063 - Sequence 175087 from Patent EP1572962.
Biochemical and Signaling Pathways
Reactome (by CSHL, EBI, and GO)
Protein P22748 (Reactome details) participates in the following event(s):
R-HSA-1237047 Carbonic anhydrase IV hydrates carbon dioxide to bicarbonate and a proton R-HSA-1237059 Carbonic anhydrase IV dehydrates bicarbonate to water and carbon dioxide R-HSA-1475017 Carbonic anhydrase dehydrates bicarbonate (plasma membrane) R-HSA-1475025 Carbonic anhydrase hydrates carbon dioxide (plasma membrane) R-HSA-1237044 Erythrocytes take up carbon dioxide and release oxygen R-HSA-1247673 Erythrocytes take up oxygen and release carbon dioxide R-HSA-1475029 Reversible hydration of carbon dioxide R-HSA-1480926 O2/CO2 exchange in erythrocytes R-HSA-1430728 Metabolism R-HSA-382551 Transport of small molecules
US Server
Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
