Pre-steady state transport by erythrocyte band 3 protein: uphill countertransport induced by the impermeant inhibitor H2DIDS

1998 ◽  
Vol 76 (5) ◽  
pp. 807-813 ◽  
Author(s):  
Michael L. Jennings ◽  
Jonathan Whitlock ◽  
Anjali Shinde
Keyword(s):  
Steady State ◽  
Band 3 ◽  
Band 3 Protein

Pre-steady state transport by erythrocyte band 3 protein: uphill countertransport induced by the impermeant inhibitor H2DIDS

1998 ◽  
Vol 76 (5) ◽  
pp. 807-813 ◽  
Author(s):  
Michael L Jennings ◽  
Jonathan Whitlock ◽  
Anjali Shinde
Keyword(s):  
Steady State ◽  
Anion Exchange ◽  
Sodium Phosphate ◽  
Band 3 ◽  
Catalytic Cycle ◽  
Band 3 Protein ◽  
Molar Excess ◽  
Transport Inhibitor ◽  
Ping Pong

Pre-steady state Cl- efflux experiments have been performed to test directly the idea that the transport inhibitor H2DIDS (4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate) binds preferentially to the outward-facing state of the transporter. Cells were equilibrated with a medium consisting of 150 mM sodium phosphate, pH 6.2, N2 atmosphere, and 80-250 µM 36Cl-. Addition of H2DIDS (10-fold molar excess compared with band 3) induces a transient efflux of Cl-, as expected if H2DIDS binds more tightly to outward-facing than to inward-facing states. The size of the H2DIDS-induced efflux depends on the Cl- concentration and is about 700 000 ions per cell at the highest concentrations tested. The size of the transient efflux is larger than would be expected if the catalytic cycle for anion exchange involved one pair of exchanging anions per band 3 dimer. These results are completely consistent with a ping-pong mechanism of anion exchange in which the catalytic cycle consists of one pair of exchanging anions per subunit of the band 3 dimer.Key words: anion exchange, erythrocyte, stilbenedisulfonate, chloride.

Rat kidney band 3 mRNA modulation in chronic respiratory acidosis

1991 ◽  
Vol 260 (2) ◽  
pp. F204-F209 ◽  
Author(s):  
J. C. Da Silva Junior ◽  
R. D. Perrone ◽  
C. A. Johns ◽  
N. E. Madias
Keyword(s):  
Steady State ◽  
Renal Cortex ◽  
Rat Kidney ◽  
Cdna Probe ◽  
Respiratory Acidosis ◽  
Band 3 ◽  
Organ Specificity ◽  
Mrna Levels ◽  
Band 3 Protein ◽  
Beta Actin

Recent evidence indicates the existence of a protein related to the erythroid chloride-bicarbonate exchanger (band 3 protein) in the basolateral aspect of type A intercalated cells of the distal nephron. To probe the possible participation of this transporter in the renal adaptation to chronic hypercapnia, we examined the steady-state abundance of band 3 mRNA in the kidney during respiratory acidosis of variable duration. Total RNA was isolated from renal cortex and medulla of rats maintained in a 10% CO2 atmosphere for 2 or 5 days and from contemporaneous controls. The RNA was analyzed by Northern blot assay using cDNA probes for band 3 and beta-actin genes. Using a 3' cDNA probe encoding the membrane-associated domain of band 3 protein that is involved in anion exchange, we found a two- to threefold increase in steady-state mRNA levels (whether or not correction for the beta-actin signals was applied) in renal cortex and medulla at 5 days of hypercapnia. Similar, but less definitive, increases were observed at the 2-day time point. Using a 5' cDNA probe encoding an erythroid-protein segment absent from the kidney band 3 major transcript, we detected meager hybridization in renal tissue and no measurable variation during hypercapnia. Use of splenic RNA as a positive control for the 5' probe disclosed marked reduction of band 3 mRNA levels in hypercapnia, indicating organ specificity of band 3 gene expression. We conclude that steady-state levels of kidney band 3 mRNA increase in chronic respiratory acidosis as a result of transcriptional or posttranscriptional regulatory mechanisms. This adaptation might be involved in the augmentation of renal acidification characteristic of chronic hypercapnia.

Fine structure of the band 3 protein in human red cell membranes: Freeze-fracture studies

1978 ◽  
Vol 8 (3) ◽  
pp. 325-335 ◽  
Author(s):  
Ronald S. Weinstein ◽  
Jena K. Khodadad ◽  
Theodore L. Steck
Keyword(s):  
Fine Structure ◽  
Cell Membranes ◽  
Freeze Fracture ◽  
Band 3 ◽  
Red Cell ◽  
Band 3 Protein ◽  
Red Cell Membranes
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