Ca2+-dependent protein phosphorylation in brush border membranes of rat kidney proximal tubules

1985 ◽  
Vol 404 (4) ◽  
pp. 358-364 ◽  
Author(s):  
Kerstin Malmstr�m ◽  
Heini Murer
Keyword(s):  
Protein Phosphorylation ◽  
Brush Border ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Brush Border Membranes ◽  
Dependent Protein ◽  
Kidney Proximal Tubules

Immunolocalization of NHE8 in rat kidney

2005 ◽  
Vol 288 (3) ◽  
pp. F530-F538 ◽  
Author(s):  
Sunita Goyal ◽  
SueAnn Mentone ◽  
Peter S. Aronson
Keyword(s):  
Proximal Tubule ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Rat Kidney ◽  
Surface Membrane ◽  
Proximal Tubules ◽  
Intense Staining ◽  
Proximal Tubule Cells ◽  
Nephron Segment ◽  
Tubule Cells

In situ hybridization studies demonstrated that Na+/H+ exchanger NHE8 is expressed in kidney proximal tubules. Although membrane fractionation studies suggested apical brush-border localization, precise membrane localization could not be definitively established. The goal of the present study was to develop isoform-specific NHE8 antibodies as a tool to directly establish the localization of NHE8 protein in the kidney by immunocytochemistry. Toward this goal, two sets of antibodies that label different NHE8 epitopes were developed. Monoclonal antibody 7A11 and polyclonal antibody Rab65 both specifically labeled NHE8 by Western blotting as well as by immunofluorescence microscopy. The immunolocalization pattern in the kidney seen with both antibodies was the same, thereby validating NHE8 specificity. In particular, NHE8 expression was observed on the apical brush-border membrane of all proximal tubules from S1 to S3. The most intense staining was evident in proximal tubules in the deeper cortex and medulla with a significant but somewhat weaker staining in superficial proximal tubules. Colocalization studies with γ-glutamyltranspeptidase and megalin indicated expression of NHE8 on both the microvillar surface membrane and the coated-pit region of proximal tubule cells, suggesting that NHE8 may be subject to endocytic retrieval and recycling. Although colocalizing in the proximal tubule with NHE3, no significant alteration in NHE8 protein expression was evident in NHE3-null mice. We conclude that NHE8 is expressed on the apical brush-border membrane of proximal tubule cells, where it may play a role in mediating or regulating ion transport in this nephron segment.

Ouabain-insensitive, Na-ATPase activity in pure suspensions of rat kidney proximal tubules

FEBS Letters ◽  
1990 ◽  
Vol 269 (1) ◽  
pp. 77-78 ◽  
Author(s):  
Reinaldo Marín ◽  
Daniela C. Gómez ◽  
Gloria A. Rodríguez ◽  
Teresa Proverbio ◽  
Fulgencio Proverbio
Keyword(s):  
Atpase Activity ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Kidney Proximal Tubules

Binding of lysozyme to brush border membranes of rat kidney

1983 ◽  
Vol 732 (2) ◽  
pp. 372-376 ◽  
Author(s):  
Gabriele Beyer ◽  
Folkert Bode ◽  
Karl Baumann
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Brush Border Membranes

The binding and degradation of insulin by brush-border membranes from rat kidney

1982 ◽  
Vol 10 (4) ◽  
pp. 220-220
Author(s):  
J. HYWEL THOMAS ◽  
PHILIP G. DAVEY ◽  
CHRISTOPHER D. G. JENKINS ◽  
DESPINA K. PAPACHRISTODOULOU
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Brush Border Membranes

Regulation of Rho protein binding to membranes by rhoGDI: inhibition of releasing activity by physiological ionic conditions

1999 ◽  
Vol 77 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Diane Bilodeau ◽  
Sylvie Lamy ◽  
Richard R Desrosiers ◽  
Denis Gingras ◽  
Richard Béliveau
Keyword(s):  
Ionic Strength ◽  
Brush Border ◽  
Rat Kidney ◽  
Regulatory Protein ◽  
Rho Proteins ◽  
Glutathione S Transferase ◽  
Free System ◽  
Brush Border Membranes ◽  
A Cell ◽  
Membrane Bound

The Rho GDP dissociation inhibitor (GDI) is an ubiquitously expressed regulatory protein involved in the cycling of Rho proteins between membrane-bound and soluble forms. Here, we characterized the Rho solubilization activity of a glutathione S-transferase (GST) - GDI fusion protein in a cell-free system derived from rat kidney. Addition of GST-GDI to kidney brush border membranes resulted in the specific release of Cdc42 and RhoA from the membranes, while RhoB and Ras were not extracted. The release of Cdc42 and RhoA by GST-GDI was dose dependent and saturable with about 50% of both RhoA and Cdc42 extracted. The unextracted Rho proteins were tightly bound to membranes and could not be solubilized by repeated GST-GDI treatment. These results demonstrated that kidney brush border membranes contained two populations of RhoA and Cdc42. Furthermore, the GST-GDI solubilizing activity on membrane-bound Cdc42 and RhoA was abolished at physiological conditions of salt and temperature in all tissues examined. When using bead-immobilized GST-GDI, KCl did not reduced the binding of Rho proteins. However, washing brush border membranes with KCl prior treatment by GST-GDI inhibited the extraction of Rho proteins. Taken together, these results suggest that the binding of GDI to membrane-bound Cdc42 and RhoA occurs easily under physiological ionic strength conditions, but a complementary factor is required to extract these proteins from membranes. These observations suggest that the shuttling activity of GDI upon Rho proteins could be normally downregulated under physiological conditions.Key words: rhoGDI, rho proteins, ionic strength, kidney.

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