brush-border membrane vesicles
نویسندگان
چکیده
The characteristics of hypoxanthine transport were examined in purified brush-border membrane vesicles isolated from guineapig kidney. Hypoxanthine uptake in the vesicles was specifically stimulated by both Na+ and an inside-negative potential, resulting in a transient accumulation of intravesicular hypoxanthine. Na+-dependent hypoxanthine influx was saturable (apparent Km 4.4 + 2.1 ,uM, Vmax 128 + 29 pmol/min per mg of protein at 100 mM NaCl and 22 °C). Guanine, thymine, 5-fluorouracil and uracil inhibited hypoxanthine uptake (K, values 1-30,M), but adenine and the nucleosides inosine and thymidine were without effect. Guanine competitively inhibited Na+-dependent hypo-
منابع مشابه
Effect of acidosis on glutamine transport by isolated rat renal brush-border and basolateral-membrane vesicles.
Glutamine uptake was examined in isolated renal brush-border and basolateral-membrane vesicles from control and acidotic rats. In brush-border vesicles from acidotic animals, there was a significant increase in the initial rate of glutamine uptake compared with that in controls. Lowering the pH of the medium increased the initial rate of glutamine uptake in brush-border vesicles from acidotic, ...
متن کاملSimultaneous isolation and characterization of brush border and basolateral membrane vesicles from bovine small intestine.
Purified brush border and basolateral membranes were isolated from homogenized intestinal enterocytes of Holstein steers by divalent cation precipitation followed by differential and sucrose density gradient centrifugation. Alkaline phosphatase and Na/K adenosine triphosphatase served as marker enzymes for the brush border and basolateral membranes, respectively. The brush border and basolatera...
متن کاملHeterogeneity of rabbit intestine brush border plasma membrane cholesterol.
Nonspecific lipid transfer protein accelerated cholesterol exchange from brush border vesicles according to a biphasic time course, but sonicated vesicles made from brush border phospholipids and glycosphingolipids showed a single phase exchange. Removal of surface protein with papain or opening brush border vesicles with deoxycholate did not abolish the biphasic exchange pattern. In brush bord...
متن کاملEstimation of apparent L-amino acid diffusion in porcine jejunal enterocyte brush border membrane vesicles.
There is an overlap of carrier-mediated L-amino acid transport and apparent simple diffusion when measured in intestinal brush border membrane vesicles. Using L-threonine and L-glutamine as representative amino acids, this study was undertaken to estimate apparent simple diffusion of L-amino acids and to establish the effective dosage of HgCl2 for completely blocking carrier-mediated L-amino ac...
متن کاملCyclic AMP-dependent protein phosphorylation in canine renal brush-border membrane vesicles is associated with decreased phosphate transport.
It is known that the administration of parathyroid hormone to dogs results in phosphaturia and decreased phosphate transport in brush-border vesicles isolated from the kidneys of those dogs. Parathyroid hormone has been shown to activate adenylate cyclase at the basal-lateral membrane of the renal proximal tubular cell. It has been postulated that parathyroid hormone-induced phosphaturia is eff...
متن کاملSelenium (selenate) transport by human placental brush border membrane vesicles
Selenium is an essential trace element required by the fetus for normal growth, therefore knowledge on the placental transport of Se is important in the context of fetal nutrition. Recent work in this laboratory has shown that selenate is a competitive inhibitor of sulphate uptake by vesicles prepared from the brush-border membrane of the syncytiotrophoblast of the human term placenta (Shennan ...
متن کامل