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Interactions of transmembrane carbonic anhydrase, CAIX, with bicarbonate transporters.
Am J Physiol Cell Physiol 2007; 293(2):C738-48AJ

Abstract

Association of some plasma membrane bicarbonate transporters with carbonic anhydrase enzymes forms a bicarbonate transport metabolon to facilitate metabolic CO(2)-HCO(3)(-) conversions and coupled HCO(3)(-) transport. The transmembrane carbonic anhydrase, CAIX, with its extracellular catalytic site, is highly expressed in parietal and other cells of gastric mucosa, suggesting a role in acid secretion. We examined in transfected HEK293 cells the functional and physical interactions between CAIX and the parietal cell Cl(-)/HCO(3)(-) exchanger AE2 or the putative Cl(-)/HCO(3)(-) exchanger SLC26A7. Coexpression of CAIX increased AE2 transport activity by 28 +/- 7% and also activated transport mediated by AE1 and AE3 (32 +/- 10 and 37 +/- 9%, respectively). In contrast, despite a transport rate comparable to that of AE3, coexpressed CAIX did not alter transport associated with SLC26A7. The CAIX-associated increase of AE2 activity did not result from altered AE2 expression or cell surface processing. CAIX was coimmunoprecipitated with the coexpressed SLC4 polypeptides AE1, AE2, and AE3, but not with SLC26A7. GST pull-down assays with a series of domain-deleted forms of CAIX revealed that the catalytic domain of CAIX mediated interaction with AE2. AE2 and CAIX colocalized in human gastric mucosa, as indicated by coimmunofluorescence. This is the first example of a functional and physical interaction between a bicarbonate transporter and a transmembrane carbonic anhydrase. We conclude that CAIX can bind to some Cl(-)/HCO(3)(-) exchangers to form a bicarbonate transport metabolon.

Authors+Show Affiliations

Membrane Protein Research Group, Dept of Physiology, University of Alberta, Edmonton, Alberta, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17652430

Citation

Morgan, Patricio E., et al. "Interactions of Transmembrane Carbonic Anhydrase, CAIX, With Bicarbonate Transporters." American Journal of Physiology. Cell Physiology, vol. 293, no. 2, 2007, pp. C738-48.
Morgan PE, Pastoreková S, Stuart-Tilley AK, et al. Interactions of transmembrane carbonic anhydrase, CAIX, with bicarbonate transporters. Am J Physiol, Cell Physiol. 2007;293(2):C738-48.
Morgan, P. E., Pastoreková, S., Stuart-Tilley, A. K., Alper, S. L., & Casey, J. R. (2007). Interactions of transmembrane carbonic anhydrase, CAIX, with bicarbonate transporters. American Journal of Physiology. Cell Physiology, 293(2), pp. C738-48.
Morgan PE, et al. Interactions of Transmembrane Carbonic Anhydrase, CAIX, With Bicarbonate Transporters. Am J Physiol, Cell Physiol. 2007;293(2):C738-48. PubMed PMID: 17652430.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Interactions of transmembrane carbonic anhydrase, CAIX, with bicarbonate transporters. AU - Morgan,Patricio E, AU - Pastoreková,Silvia, AU - Stuart-Tilley,Alan K, AU - Alper,Seth L, AU - Casey,Joseph R, Y1 - 2007/07/25/ PY - 2007/7/27/pubmed PY - 2007/9/21/medline PY - 2007/7/27/entrez SP - C738 EP - 48 JF - American journal of physiology. Cell physiology JO - Am. J. Physiol., Cell Physiol. VL - 293 IS - 2 N2 - Association of some plasma membrane bicarbonate transporters with carbonic anhydrase enzymes forms a bicarbonate transport metabolon to facilitate metabolic CO(2)-HCO(3)(-) conversions and coupled HCO(3)(-) transport. The transmembrane carbonic anhydrase, CAIX, with its extracellular catalytic site, is highly expressed in parietal and other cells of gastric mucosa, suggesting a role in acid secretion. We examined in transfected HEK293 cells the functional and physical interactions between CAIX and the parietal cell Cl(-)/HCO(3)(-) exchanger AE2 or the putative Cl(-)/HCO(3)(-) exchanger SLC26A7. Coexpression of CAIX increased AE2 transport activity by 28 +/- 7% and also activated transport mediated by AE1 and AE3 (32 +/- 10 and 37 +/- 9%, respectively). In contrast, despite a transport rate comparable to that of AE3, coexpressed CAIX did not alter transport associated with SLC26A7. The CAIX-associated increase of AE2 activity did not result from altered AE2 expression or cell surface processing. CAIX was coimmunoprecipitated with the coexpressed SLC4 polypeptides AE1, AE2, and AE3, but not with SLC26A7. GST pull-down assays with a series of domain-deleted forms of CAIX revealed that the catalytic domain of CAIX mediated interaction with AE2. AE2 and CAIX colocalized in human gastric mucosa, as indicated by coimmunofluorescence. This is the first example of a functional and physical interaction between a bicarbonate transporter and a transmembrane carbonic anhydrase. We conclude that CAIX can bind to some Cl(-)/HCO(3)(-) exchangers to form a bicarbonate transport metabolon. SN - 0363-6143 UR - https://www.unboundmedicine.com/medline/citation/17652430/Interactions_of_transmembrane_carbonic_anhydrase_CAIX_with_bicarbonate_transporters_ L2 - http://www.physiology.org/doi/full/10.1152/ajpcell.00157.2007?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -