Transport mechanisms of a glycoside, p-nitrophenyl-β-d-glucopyranoside, across rat small intestinal brush-border membranes
| Autor: | Takashi Mizuma, Sohei Higashi, Shoji Awazu, Toshimasa Ohnishi |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
Male
Brush border Disaccharide Biophysics (Rat) Biochemistry Binding Competitive chemistry.chemical_compound Glucosides Brush-border membrane vesicle Intestine Small medicine Animals Intestinal Mucosa Rats Wistar chemistry.chemical_classification Chromatography Binding Sites Microvilli Osmolar Concentration Glycoside Biological Transport Cell Biology Small intestine Alkaline Phosphatase Uridine Rats medicine.anatomical_structure Membrane Glucose β-glucoside transport chemistry Active transport Leucine Subcellular Fractions |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. (2):192-198 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/S0005-2736(97)00262-9 |
| Popis: | We examined the mechanism of p-nitrophenyl-β- d -glucopyranoside (p-NP-β- d -Glc) transport in brush-border membrane vesicles from rat small intestine. The initial uptake rate showed an overshoot phenomenon in the presence of an inwardly directed sodium-ion concentration gradient. The overshoot disappeared when the sodium-ion concentration gradient was replaced with a potassium ion concentration gradient. d -Glucose and p-NP-β- d -Glc analogues inhibited the uptake, whereas uridine, leucine and disaccharide did not. Data on the concentration dependence of p-NP-β- d -Glc uptake indicated that two carrier-mediated systems are involved. The uptake via the high-affinity site required an inwardly directed sodium-ion concentration gradient, while the uptake via the low-affinity site proceeded such a gradient. d -Glucose competitively inhibited the initial uptake of p-NP-β- d -Glc via the high-affinity site with a Ki value of 301 μM. The p-NP-β- d -Glc is transported in the small intestine via both the same carrier-mediated transport system that takes up d -glucose and a distinct low-affinity carrier-mediated transport system. |
| Databáze: | OpenAIRE |
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