The Significance of Folate Binding Proteins in Folate Metabolism

Waxman, Samuel; Schreiber, Carol; Rubinoff, Mitchell

doi:10.1007/978-1-4613-9928-5_3

Cited by 15 publications

(9 citation statements)

References 46 publications

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“…Proteins which specifically bind folate have previously been isolated from various body fluids and tissues (33,20) including cow's milk (14,30). The function of these proteins is not yet fully understood, but they may play a role in the utilization of folic acid and in the storage and transport of this vitamin (33).…”

Section: Introductionmentioning

confidence: 99%

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Isolation and characterization of the folate-binding protein from cow's milk

Svendsen

Martin

Pedersen

et al. 1979

Carlsberg Res. Commun.

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Section: Introductionmentioning

confidence: 99%

“…The function of these proteins is not yet fully understood, but they may play a role in the utilization of folic acid and in the storage and transport of this vitamin (33). Binding studies have shown that a protein from cow's milk binds folate in a cooperative manner over a wide range of pH (13,14,19).…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of the folate-binding protein from cow's milk

Svendsen

Martin

Pedersen

et al. 1979

Carlsberg Res. Commun.

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“…High molecular weight (MW 100,000 -200,000) and low molecular weight (MW 25,00 -40,000) proteins, which specifically bind folate are present in various body fluids and tissues (4,10). Low molecular weight folate binding proteins (FBP) have been isolated from cow's milk (6,7,8), goat's milk (5) and human milk (1,3,9) which in addition contains a high molecular weight FBP (1,3,9).…”

Section: Introductionmentioning

confidence: 99%

Amino acid sequence homology between human and bovine low molecular weight folate binding protein isolated from milk

Svendsen

Hansen

Holm

et al. 1982

Carlsberg Res. Commun.

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The partial amino acid sequence of a low molecular weight folate binding protein from human milk has been determined from N-terminal sequencing of the native protein and isolated cyanogen bromide fragments. A molecular weight of approximately 30,000 is estimated on the basis of amino acid composition and sequence homology with the low-molecular weight folate binder isolated from cow's milk. Preliminary studies with a large molecular weight folate binding protein have shown that the N-terminal amino acid sequence is identical with that of the low molecular binder.

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“…The folate enterohepatic circulation may be completed by the intestinal reab sorption of the folate by FABP present in the small intestinal mucosal brush border [15] . Interestingly, perturbations of the en terohepatic circulation for folate [24] as well as elevations of serum FABP [6,28] have been reported in alcoholics and may be re lated to the folate deficiency often encoun tered.…”

Section: Discussionmentioning

confidence: 99%

“…Unlike the R-type vitamin B12 binding proteins which are secreted into the bile bound to vitamin B12 [2], FABP is dissociated from the folic acid and catabolized in the liver. The folic acid is re duced and methylated and is then secreted into the bile in the form of 5CH3PteGlu [14] , which has a lower affinity for FABP [28]. The folate enterohepatic circulation may be completed by the intestinal reab sorption of the folate by FABP present in the small intestinal mucosal brush border [15] .…”

Section: Discussionmentioning

confidence: 99%

Effect of a Folate–Binding Protein on the Plasma Transport and Tissue Distribution of Folic Acid

Rubinoff¹,

Abramson²,

Schreiber³

et al. 1981

Acta Haematol

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Folic acid (³H-pteroylglutamic acid or ⁷⁵Se-selenofolate) administered free or bound to folate-binding protein (FABP) was rapidly cleared from the plasma but the plasma survival when bound to FABP was longer than unbound during the initial 5 min. ⁷⁵Se-folate bound to FABP is more rapidly taken up by the liver than when administered as free ⁷³Se-folate. ¹²⁵I-labeled FABP was rapidly cleared from the plasma (90% in 5 min). The rapid uptake of FABP, a sialoglycoprotein, was inhibited by the preadministration of desialyzed fetuin. Following the hepatic uptake of ⁷⁵Se-folate/FABP, only free ⁷⁵Se-folate was found in the bile. The total biliary secretion of ⁷⁵Se-folate over 240 min was 63% when administered bound to FABP and 33% when administered as free ⁷⁵Se-folate. The liver retained 33.5% of the ¹²⁵I activity 5 min following the administration of ¹²⁵I-FABP, while only 4.46% of the ¹²⁵I activity was secreted into the bile over 180 min. This data suggests that FABP may play an important role in the enterohepatic circulation of folates by directing nonmethylated folates to the liver.

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The Significance of Folate Binding Proteins in Folate Metabolism

Cited by 15 publications

References 46 publications

Isolation and characterization of the folate-binding protein from cow's milk

Isolation and characterization of the folate-binding protein from cow's milk

Amino acid sequence homology between human and bovine low molecular weight folate binding protein isolated from milk

Effect of a Folate–Binding Protein on the Plasma Transport and Tissue Distribution of Folic Acid

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