scholarly journals Active Sugar Transport by the Small Intestine

1968 ◽  
Vol 52 (3) ◽  
pp. 482-494 ◽  
Author(s):  
Robert G. Faust ◽  
Mary G. Leadbetter ◽  
Regina K. Plenge ◽  
Alston J. McCaslin
Keyword(s):  
Small Intestine ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sugar Transport ◽  
Initial Step ◽  
Inhibitory Effect ◽  
Glucose Binding ◽  
Brush Borders

Tris-disrupted and intact brush border membrane preparations from mucosa of hamster jejunum were capable of preferentially binding actively transported D-glucose in a similar manner. Density gradient centrifugation of the Tris-disrupted brush borders indicated that D-glucose was bound to a fraction containing the cores or inner material of the microvilli. The properties of this binding were examined with the Tris-disrupted brush border preparation. Actively transported sugars competitively inhibited preferential D-glucose binding, whereas no effect was observed with nonactively transported sugars. Neither actively nor nonactively transported amino acids affected D-glucose binding. D-Glucosamine, which is not actively transported, was inhibitory to preferential D-glucose binding as well as to the active transport of D-glucose by everted sacs of hamster jejunum. No inhibitory effect was observed with the same concentration of D-galactosamine. Preferential D-glucose binding was also inhibited by sulfhydryl-reacting compounds, Ca2+, and Li+ ions. On the other hand, Mg2+ was shown to be stimulatory and Na+, NH4+, and K+ had no effect on this phenomenon. The results of these experiments suggest that preferential D-glucose binding to brush borders is related to the initial step in active sugar transport by the small intestine.

Galactosyltransferase activity is not localized to the brush border membrane of human small intestine

1986 ◽  
Vol 6 (2) ◽  
pp. 171-175 ◽  
Author(s):  
Frances Boyle ◽  
Susan Snape ◽  
Paul Duane ◽  
Neil Cook ◽  
Timothy Peters
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Subcellular Fractionation ◽  
Equilibrium Density ◽  
Sucrose Density Gradient Centrifugation ◽  
Human Small Intestine ◽  
Immunocytochemical Techniques

A recent report [Roth et al. (1985) J. Cell Biol.100: 118–125], using immunocytochemical techniques, calimed that human duodenal galactosyltransferase is located predominantly on the external aspect of enterocyte brush border membranes. Analytical subcellular fractionation by sucrose density gradient centrifugation of human jejunum biopsy homogenates demonstrated that galactosyltransferase activity is localized to the Golgi fraction (equilibrium density of 1.14 g cm−3) and is not found in significant amounts in the brush border membrane (equilibrium density of 1.22 g cm−3).

Hydrolysis and transglycosylation activities of glycosidases from small intestine brush-border membrane vesicles

2021 ◽  
Vol 139 ◽  
pp. 109940
Author(s):  
Lesbia Cristina Julio-Gonzalez ◽  
F. Javier Moreno ◽  
María Luisa Jimeno ◽  
Elisa G. Doyagüez ◽  
Agustín Olano ◽  
...  
Keyword(s):  
Small Intestine ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles

Labeling of a glucose binding protein in the rabbit intestinal brush border membrane

1978 ◽  
Vol 56 (5) ◽  
pp. 760-770 ◽  
Author(s):  
J. Lemaire ◽  
D. Maestracci
Keyword(s):  
Molecular Weight ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Binding Protein ◽  
Electrophoretic Pattern ◽  
Protein Band ◽  
Relative Mobility ◽  
Intestinal Brush Border ◽  
Glucose Binding ◽  
Glucose Binding Protein

Using a double labeling method based on the method of Thomas (Thomas, L. 1973. Isolation of N-ethylmaleimide-labeled phloridzin-sensitive D-glucose binding protein of brash border membrane from rat kidney cortex. Biochim. Biophys. Acta, 291, 454–464.), with radioactive N-ethylmaleimide ([3H]NEM and [14C]NEM) in the presence and absence of D-glucose, a protein band which is periodic acid – Schiff staining insensitive and which has a relative mobility (Rm) of 0.55 (corresponding to a molecular weight of 51 000 daltons) as determined by sodium dodecyl sulfate (SDS) electrophoresis was labeled preferentially.When radioactive p-hydroxymercuriphenylsulfonate ([203Hg]PCMBS) is used in the presence and absence of D-glucose, as described by Smith et al. (SMITH, M. W., FERGUSON, D. R., and BURTON, K. A. 1975. Glucose- and phloridzin-protected thiol groups in pig intestinal brush border membranes. Biochern. J. 147, 617–619.), a protein band which has a relative mobility of 0.62 and a corresponding molecular weight of 42 000 daltons was labeled.Control experiments have shown that increasing concentrations of nonradioactive NEM (0.1–5.0 mM) do not substantially modify the electrophoretic pattern of SDS-solubilized brush border membrane. Nonradioactive PCMBS (0.1–10 mM), on the other hand, modifies the electrophoretic pattern and especially causes a change in relative mobility of the 0.55 protein band which migrates after 1 mM PCMBS treatment with a Rm of 0.62.The effect of 1 mM PCMBS can be reversed by adding L-cysteine or dithiotreitol.Actin extracted from rabbit muscle migrates with the same Rm as the 0.55 protein band in our electrophoretic conditions.

Acute hypertension provokes internalization of proximal tubule NHE3 without inhibition of transport activity

2002 ◽  
Vol 282 (4) ◽  
pp. F730-F740 ◽  
Author(s):  
Li Yang ◽  
Patrick K. K. Leong ◽  
Jennifer O. Chen ◽  
Nilem Patel ◽  
Sarah F. Hamm-Alvarez ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Brush Border ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Transport Activity ◽  
Sprague Dawley ◽  
Acute Hypertension ◽  
Sprague Dawley Rats ◽  
Cortical Membranes ◽  
Apical Membranes

Acute hypertension rapidly decreases proximal tubule (PT) Na+ reabsorption, facilitated by a redistribution of PT Na+/H+exchangers (NHE3) out of the apical brush border, increasing NaCl at the macula densa, the signal for autoregulation of renal blood flow and GFR. This study aimed to determine whether NHE3 activity per transporter decreases during acute hypertension and the time dependence of the response. Blood pressure was elevated by 50–60 mmHg in male Sprague-Dawley rats for 5 or 30 min by constricting arteries. Renal cortical membranes were fractionated by density gradient centrifugation. NHE3 transport activity was assayed as the rate of appearance of acridine orange (AO) from AO-loaded vesicles in response to an inwardly directed Na+ gradient. After 5-min hypertension, 20% of total NHE3 protein, assayed by immunoblot, redistributed from low-density apical membranes to middensity membranes enriched in intermicrovillar cleft markers; by 30 min, a similar percentage shifted to heavier density membranes containing markers of endosomes. NHE3 activity shifted to higher density membranes along with NHE3 protein, that is, no change in activity/transporter during acute hypertension. Confocal analysis of NHE3 distribution also verified removal from apical microvilli and appearance in subapical vesicles. We conclude that the decrease in renal PT Na+ transport during acute hypertension is mediated by removal of transport-competent NHE3 from the apical brush border to subapical and internal reserves.

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