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Subcellular distribution of PRibPP synthetase activity of rat intestinal mucosa
Abstract:
5-Phosphoribosyl 1-pyrophosphate synthetase (PRibPP synthetase EC 2.7.6.1) isolated from rat intestinal mucosa was found to be membrane associated. The subcellular distribution of PRibPP synthetase activity seems to parallel that of gamma-glutamyl transpeptidase, indicating it to be in the brush border. The tip cells of rat intestinal mucosa were richer in PRibPP synthetase than the crypt cells. Chromatography of a Triton-solubilized particulate fraction unmasked a peak of hypoxanthine phosphoribosyltransferase activity that was not detectable before. The activity, too, was concentrated in the brush border. The coexistence of these two activities in the fraction of the bowl involved in absorption has led to the suggestin that the synthetase and phosphoribosyl-transferase are part of a coupled transport system.
Insights
5-Phosphoribosyl 1-pyrophosphate synthetase (PRibPP synthetase) is located in the brush border of rat intestinal cells. Its presence alongside hypoxanthine phosphoribosyltransferase suggests a coupled transport system for absorption.
Area of Science:
- Biochemistry
- Cell Biology
- Gastroenterology
Background:
- 5-Phosphoribosyl 1-pyrophosphate synthetase (PRibPP synthetase) is crucial for purine and pyrimidine biosynthesis.
- Its localization within the intestinal mucosa is not well-established.
Purpose of the Study:
- To investigate the subcellular localization of PRibPP synthetase in rat intestinal mucosa.
- To explore the potential functional relationship between PRibPP synthetase and hypoxanthine phosphoribosyltransferase.
Main Methods:
- Isolation of PRibPP synthetase from rat intestinal mucosa.
- Subcellular fractionation and enzyme activity assays.
- Chromatography of Triton-solubilized particulate fractions.
Main Results:
- PRibPP synthetase activity was found to be membrane-associated and concentrated in the brush border of intestinal tip cells.
- Hypoxanthine phosphoribosyltransferase activity was also detected in the brush border fraction.
- The distribution of PRibPP synthetase paralleled that of gamma-glutamyl transpeptidase.
Conclusions:
- PRibPP synthetase is localized in the brush border of rat intestinal cells.
- The co-localization with hypoxanthine phosphoribosyltransferase suggests a potential coupled transport system involved in nutrient absorption.