scholarly journals Folic acid and folate binding protein in pregnancy.

1977 ◽  
Vol 23 (5) ◽  
pp. 447-453 ◽  
Author(s):  
Suvit AREEKUL ◽  
Petcharin YAMARAT ◽  
Manit VONGYUTHITHUM
1987 ◽  
Vol 252 (4) ◽  
pp. F757-F760 ◽  
Author(s):  
J. Selhub ◽  
S. Nakamura ◽  
F. A. Carone

Surface proximal convoluted tubules (PCT) in rats were microinfused in situ with [3H]folic acid to study the role of folate binding protein (FBP) in the kidney brush-border membrane for renal conservation and transport of folate [3H]folic acid absorption was linearly related to tubular length of PCT and occurred largely in this segment of the tubule. Unlabeled folate derivatives inhibited [3H]folic acid absorption, the extent of which was dependent on the type of unlabeled folate used and its concentration. At equivalent concentrations, inhibition was most effective with unlabeled folic acid, slightly lower than with 5-methyltetrahydrofolate and least effective with methotrexate. Comparisons between [3H]folic acid absorption before and after infusion of a saturating dose of unlabeled folic acid or repetitive injections of [3H]folic acid into the same tubular site revealed continuous and rapid regeneration of unsaturated folic acid uptake sites with an apparent half-life of 28.75 +/- 8.75 s. Determination of [3H] retained in the tubule at various periods after microinfusion of [3H]folic acid revealed slow cellular disappearance with an apparent half-life of 47.3 +/- 5.4 min. It is proposed that the brush-border FBP functions as a receptor of infused folic acid and that following the binding of the ligand the folic acid/FBP complex undergoes a rapid change that results in the internalization of folic acid and regeneration of unsaturated binding sites at the membrane surface. Internalized folic acid is slowly released into renal capillaries.


Nanoscale ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 2603-2615 ◽  
Author(s):  
Rachel L. Merzel ◽  
Sarah M. Boutom ◽  
Junjie Chen ◽  
Carolina Frey ◽  
Kerby Shedden ◽  
...  

Blood ◽  
1975 ◽  
Vol 46 (6) ◽  
pp. 855-867 ◽  
Author(s):  
CD Fischer ◽  
M da Costa ◽  
SP Rothenberg

Previous studies have demonstrated that some chronic myelogenous leukemia cells contain a macromolecular binding factor for folic acid. This binder, which previously was believed to be a single factor, has now been resolved into two distinct binding proteins. Separation of each binder was obtained by DEAE chromatography of the partially purified lysate of chronic myelogenous leukemia cells. One binder has a molecular weight of 30;000–35,000, and the second binder has a molecular weight of 40,000-45,000. Both proteins bind the mono-, di-, and triglutamates of folic acid, N10-methyl-folate, dihydro-folate, and N5-methyltetrahydrofolate. Neither binder has determinants for N5- formyltetrahydrofolate or methotrexate. The preferred substrates for both binders appear to be the fully oxidized and partially reduced folates rather than the fully reduced folates. The lower-molecular- weight folate binding protein shows reversible binding with partially and fully reduced folates but irreversible binding with oxidized folates. This property suggests that this binder may have some function in the transport and storage of folate. The higher-molecular-weight folate binding protein, however, has only slight reversibility of binding with the partially and fully reduced folates, and it is therefore more difficult to postulate a physiologic function for this binding factor.


1990 ◽  
Vol 267 (1) ◽  
pp. 249-252 ◽  
Author(s):  
A M Reisenauer

A specific transport system for folate and a high-affinity folate-binding protein have been identified in pig intestinal brush-border membranes. To determine if the binding protein plays a role in folic acid (PteGlu) uptake in to the cell, the inactivation of folate binding and transport by N-hydroxysuccinimide esters of folic acid (NHS-PteGlu) was compared. In addition, the number of brush-border proteins modified by the affinity reagent was assessed. Brush-border vesicles were incubated with various concentrations of NHS-PteGlu or NHS-methotrexate. Transport and binding of [3H]PteGlu by the vesicles were measured at 37 and 4 degrees C respectively by using the vacuum-filtration technique. NHS-methotrexate and NHS-PteGlu specifically inhibited PteGlu transport. Incubating the vesicles with 1 microM-NHS-PteGlu inactivated [3H]PteGlu transport by 60% and binding by 80%. Half-maximal inhibition of both transport and binding was observed at similar concentrations of the affinity reagent (0.05 and 0.07 microM-NHS-PteGlu respectively). Treating the vesicles with radiolabelled NHS-PteGlu followed by gel electrophoresis and autoradiography revealed a specifically labelled protein with an Mr of 56,000. These results indicate that the intestinal folate-binding and transport proteins are identical and that the function of the folate-binding protein is to transport folate into the cell.


2010 ◽  
Vol 98 (3) ◽  
pp. 596a
Author(s):  
L. Devon Triplett ◽  
Daniel Q. McNerny ◽  
J. Gabriel Grodzicki ◽  
Kumar Sinniah ◽  
Mark M. Banaszak Holl ◽  
...  

2016 ◽  
Vol 28 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Junjie Chen ◽  
Sarah Klem ◽  
Alexis K. Jones ◽  
Bradford Orr ◽  
Mark M. Banaszak Holl

Sign in / Sign up

Export Citation Format

Share Document