Characterization of oxalate transport by the human erythrocyte band 3 protein

Content Provider	Semantic Scholar
Author	Jennings, Michael L. Adame, Maria Fernanda
Copyright Year	1996
Abstract	This paper describes characteristics of the transport of oxalate across the human erythrocyte membrane. Treatment of cells with low concentrations of H2DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate) inhibits Cl(-)-Cl- and oxalate-oxalate exchange to the same extent, suggesting that band 3 is the major transport pathway for oxalate. The kinetics of oxalate and Cl- self-exchange fluxes indicate that the two ions compete for a common transport site; the apparent Cl- affinity is two to three times higher than that of oxalate. The net exchange of oxalate for Cl-, in either direction, is accompanied by a flux of H+ with oxalate, as is also true of net Cl(-)-SO4(2-) exchange. The transport of oxalate, however, is much faster than that of SO4(2-) or other divalent anions. Oxalate influx into Cl(-)-containing cells has an extracellular pH optimum of approximately 5.5 at 0 degrees C. At extracellular pH below 5.5 (neutral intracellular pH), net Cl(-)-oxalate exchange is nearly as fast as Cl(-)-Cl- exchange. The rapid Cl(-)-oxalate exchange at acid extracellular pH is not likely to be a consequence of Cl- exchange for monovalent oxalate (HOOC-COO-; pKa = 4.2) because monocarboxylates of similar structure exchange for Cl- much more slowly than does oxalate. The activation energy of Cl(-)-oxalate exchange is about 35 kCal/mol at temperatures between 0 and 15 degrees C; the rapid oxalate influx is therefore not a consequence of a low activation energy. The protein phosphatase inhibitor okadaic acid has no detectable effect on oxalate self-exchange, in contrast to a recent finding in another laboratory (Baggio, B., L. Bordin, G. Clari, G. Gambaro, and V. Moret. 1993. Biochim. Biophys. Acta. 1148:157-160.); our data provide no evidence for physiological regulation of anion exchange in red cells.
Starting Page	145
Ending Page	159
Page Count	15
File Format	PDF HTM / HTML
PubMed reference number	8741736
Volume Number	107
Journal	The Journal of general physiology
Alternate Webpage(s)	http://ftp.ncbi.nlm.nih.gov/pub/pmc/19/4d/jg1071145.PMC2219244.pdf
Language	English
Access Restriction	Open
Subject Keyword	Anion Exchange Protein 1, Erythrocyte Anions Chloride Ion DUOXA1 gene Ephrin Type-B Receptor 1, human Erythrocyte Membrane Erythrocytes Iontophoresis Okadaic Acid Oxalate measurement Oxalates Protein Phosphatase Inhibitor Succinic Acid dihydro-DIDS oxalate transport
Content Type	Text
Resource Type	Article