In vitro Phosphorylation of Rat Kidney Proximal Tubular Brush Border Membranes

1985 ◽  
Vol 8 (1) ◽  
pp. 19-29
Author(s):  
Jürg Biber ◽  
Vito Sealera ◽  
Heini Murer
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Brush Border Membranes ◽  
Proximal Tubular

Phosphorylation of rat kidney proximal tubular brush border membranes

1983 ◽  
Vol 398 (3) ◽  
pp. 221-226 ◽  
Author(s):  
J. Biber ◽  
K. Malmstr�m ◽  
V. Scalera ◽  
H. Murer
Keyword(s):  
Brush Border ◽  
Rat Kidney ◽  
Brush Border Membranes ◽  
Proximal Tubular

Guanine nucleotides protect Rho proteins from endogenous proteolytic degradation in renal membranes

1998 ◽  
Vol 76 (1) ◽  
pp. 63-72
Author(s):  
Richard R Desrosiers ◽  
France Gauthier ◽  
Wei Lin ◽  
Richard Béliveau
Keyword(s):  
Proteolytic Activity ◽  
Brush Border ◽  
Rat Kidney ◽  
Proteolytic Degradation ◽  
Rat Tissues ◽  
Rho Proteins ◽  
Brush Border Membranes ◽  
Membrane Treatment ◽  
Kidney Liver

Purified membrane fractions have been widely used for the study of the factors regulating the functions of Rho small GTP-binding proteins. Using brush border membranes from the rat kidney as a model, we observed that in vitro incubation of these membranes resulted in time- and temperature-dependent proteolytic degradation of Cdc42 and RhoA. Treatment of kidney brush border membranes with various nucleotides showed that GDP and GTP weakly protected Cdc42 but not RhoA and that their nonhydrolyzable counterparts, guanosine 5'-O-[β-thio]diphosphate (GDPβS) and guanosine 5'-O-[γ-thio]triphosphate (GTPγS), were highly efficient in protecting both proteins from endogenous proteolytic activity whereas ADP and ATP were without effect. GTPγS also protected Cdc42 and RhoA from proteolytic degradation in crude cell membranes from several rat tissues including intestine, kidney, liver, and testis. In addition, Cdc42 and RhoA associated with brush border membranes were largely resistant to increased proteolytic degradation induced by membrane treatment with the denaturing reagent urea as well as to added trypsin when incubated in the presence of GTPγS. In brush border membranes, the resistance to endo- and exo-genous proteolytic activity conferred by GTPγS was usually lower for RhoA than for Cdc42. GTPγS also protected recombinant Cdc42 and RhoA from the action of proteases associated with brush border membranes. The only protease inhibitor protecting Cdc42 but not RhoA from proteolytic degradation in brush border membranes was the synthetic peptide acetyl-Tyr-Val-Ala-Asp-aldehyde, a selective inhibitor of interleukin-1β-converting enzyme. This latter result showed that different proteases cleaved the two Rho proteins. Taken together, these results suggest that the GTPγS-bound forms of Cdc42 and RhoA are maintained in a conformation that protects them from proteases found in many cell membranes.Key words: rho proteins, GTP, proteolysis, kidney.

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

Mechanism of maleic acid-induced glucosuria in dog kidney

1976 ◽  
Vol 231 (4) ◽  
pp. 1024-1032 ◽  
Author(s):  
M Silverman ◽  
L Huang
Keyword(s):  
Brush Border ◽  
Maleic Acid ◽  
Brush Border Membrane ◽  
Multiple Indicator Dilution ◽  
Dog Kidney ◽  
Proximal Tubular ◽  
Multiple Indicator ◽  
Prior Administration

The multiple indicator-dilution technique in vivo and isolated brush-border membranes in vitro have been used to explore the mechanism of maleic acid-induced glucosuria in dog kidney. The interaction of D-glucose with the antiluminal membrane from the peritubular fluid surface is unaltered. It is demonstrated that alpha-methyl-D-glucoside (alpha MG) enters and exits from the proximal tubular cell only across the brush-border membrane. Then using alphaMG as a reference indicator, it is shown that maleic acid does not cause complete inhibition of D-glucose interaction with the antiluminal membrane from the cytoplasmic surface. The binding of [3H]phlorizin both in vivo and in vitro is not affected by prior administration of maleic acid, indicating that D-glucose interaction with the outside surface of the brush border is also not affected by maleic acid. The data are therefore consistent with the concept that maleic acid-induced glucosuria is due either to i) partial inhibition of D-glucose movement from cytoplasm across the antiluminal membrane into the blood, ii) stimulated movement back across the brush-border membrane into urine, or iii) a combination of the two effects.

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

Cystine and lysine reabsorption in the isolated perfused rat kidney

1989 ◽  
Vol 256 (5) ◽  
pp. F901-F908
Author(s):  
K. A. Roby ◽  
S. Segal
Keyword(s):  
Transport System ◽  
Brush Border ◽  
Rat Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Transport Studies ◽  
Perfused Rat Kidney ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular

Renal tubular reabsorption of cystine and lysine were studied in the isolated perfused rat kidney to bridge the gap between in vivo clearance studies, and in vitro transport studies of tubule fragments, cells, and brush-border membranes. Lysine was reabsorped by a saturable transport system shared by the dibasics. Cystine was also reabsorbed by a saturable transport system, which was shared in part by the dibasics (maximum inhibition 30%). The lysine threshold (Fmin) was 0.9 mumol.min-1.g-1, with a tubular maximum (TM) of 2.4 mumol.min-1.g-1. The cystine Fmin was 0.06 mumol.min-1.g-1; the TM could not be estimated because it was above the limit of cystine solubility. There was no evidence of cystine ,secretion.- The gamma-glutamyltransferase inhibitor, AT-125, decreased cystine excretion, but only in the presence of glutathione, glycine, glutamate, and the diabasic amino acids. This suggests that cystine from glutathione degradation at the brush border may contribute to urinary cystine (an explanation of the phenomenon of cystine secretion), but only under certain conditions.

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