Folate transporter

The stability of [3, 5, 7,9-3H]folic acid (Fignre 10.10) was analyzed to determine whether the varied and conflicting resnlts regarding the characteristics of folate transport in L1210 cells conld be due to impurities in the labeled snbstrate [19]. The susceptibility of [3, 5, 7,9-3H]folic acid to decomposition during storage at -20°C... 

Prasad, P. D., et al. Molecular cloning of the human placental folate transporter. Biochem. Biophys. Res. Commun. 

Nguyen, T. T., et al. Human intestinal folate transport cloning, expression, and distribution of complementary RNA. Gastroenterology 1997, 3 32, 783-791. 

Said, H. M., et al. Intestinal folate transport identification of a cDNA involved in folate transport and the functional expression and distribution of its mRNA. Biochim. Biophys. Acta... 

Roy, K., et al. Chromosomal localization of the murine RFC-1 gene encoding a folate transporter and its amplification in an antifolate resistant variant overproducing the transporter. Cancer Genet. Cytogenet. 1998, 305, 29-38. 

Itoh, T., et al. Stereoselectivity of the folate transporter in rabbit small intestine studies with amethopterin enantiomers. Chirality 2001, 13, 164-169. 

Dutta, B., et al. Cloning of the human thiamine transporter, a member of the folate transporter family. J. Biol. Chem. 1999, 274, 31925-31929. 

Recently it was shown that folate transport from the basolateral site occurs as readily as that from the luminal site, indicating that changes in secretion can mediate excess urinary folate excretion [56]. 

Ramaekers VT, Steen-Ingemann H, Holm J, Opladen T, Senderek J, Hausler M, Heimann G, Fowler B, Maiwald R, Blau N (2003) Reduced folate transport to the brain in Rett syndrome. Neurology 61 506-514... 

Chen ZS, Lee K, Walther S, et al. Analysis of methotrexate and folate transport by multidrug resistance protein 4 (ABCC4) MRP4 is a component of the methotrexate efflux system. Cancer Res 2002 62 3144—3150. 

D. Fumonisin and accumulation of bioactive sphingoid base-l-phosphates 164 E. Fumonisin depletion of glycosphingolipids and disruption of folate transport 166 VI. Conclusions 170 References 171... 

E. Fumonisin depletion of glycosphingolipids and disruption of folate transport... 

Fumonisin inhibition of de novo sphingolipid biosynthesis (Merrill et ah, 2001 Riley et ah, 1996), resulting in depletion of complex glyco-sphingolipids, disruption of lipid rafts, and compromised folate transport via Folrl, which may have significant implications with respect to developmental anomalies such as NTDs (Hansen et ah, 2003 Piedrahita... 

Marasas, W. F., Riley, R. T., Hendricks, K. A., Stevens, V. L., Sadler, T. W., Gelineau-van Waes, J., Missmer, S. A., Cabrera, J., Torres, O., Gelderblom, W. C., Allegood, J., Martinez, C., et al. (2004). Fumonisins disrupt sphingolipid metabolism, folate transport, and neural tube development in embryo culture and in vivo A potential risk factor for human neural tube defects among populations consuming fumonisin-contaminated maize. J. Nutr. 134(4), 711-716. 

Miotti, S., Bagnoli, M., Ottone, F., Tomassetti, A., Colnaghi, M. I., and Canevari, S. (1997). Simultaneous activity of two different mechanisms of folate transport in ovarian carcinoma cell lines. J. Cell Biochem. 65(4), 479 191. 

The reduced folate transporter is a transmembrane protein with a high affinity for methyl-tetrahydrofolate and a low affinity for other vitamers. It is especially active in enterocytes and renal tubule epithelium, but is also found in other cells (Sirotnak and Tolner, 1999). 

Barber RC, Lammer EJ> Shaw GM> Greer KA, Finnell RH. The role of folate transport and metabolism in neural tube defect risk. Mol Genet Metab 1999 66 ... 

Inherited disorders of folate transport and metabolism include defects in folate carrier (hereditary folate malabsorption, previously discussed), deficiency of N, N °-methylene FH4 reductase (Chapter 17), or functional deficiency of N -methyl FH4 methyltransferase due to defects... 

Figure 4-4. Intestinal absorption of dietary folates (THF-[Gluy and foUc acid (F) from fortified cereal products and vitamin supplements. In the duodenum and upper jejunum, extra glutamate residues are cleaved by conjugases (y-glutamyl carboxypeptidases). Folate (F) and reduced folate (THF) are absorbed by a proton-coupled, high affinity folate transporter into the mucosal cell, converted to N -methyl THF and exported into the portal circulation. N -methyl THF is taken up into cells by facilitative diffusion, converted to THF by the Bj -requiring methionine synthase and then converted to a polyglutamate.

Que A., et al. Identification of an intestinal folate transporter and the molecular basis for hereditary folate malabsorption. Cell 2006 127 917-28. 

Lipoic acid metabolism LipT - iipoate transporter Folate biosynthesis FolT/EcfAAT - folate transporter... 

Surprisingly, a method of antifolate resistance commonly cited in tumor cells is gene amplification resulting in increased target protein and decreased anti-folate efficacy, which has yet to be identified in any clinically relevant isolate. A further difference in antifolate resistance between mammalian cells and the parasitic cell is altered polyglutamation of die antifolate drugs. In mammalian cells, folates are taken up by a folate transport system and once inside the cell are poly-glutamated to trap the folates intracellularly. A reported mechanism of resistance in the cancer cell is the loss of... 

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