Methotrexate can lower the concentration of folate in plasma, and thus may cause a megaloblastic anaemia. Other co-factors of tetrahydrofolate are responsible for metabolic reactions such amino acid interconversion (e.g., the conversion of homocysteine to methionine [a vitamin B12-dependent process] and the conversion of serine to glycine), histidine metabolism, formate generation and synthesis of essential purines. Folate molecules are highly hydrophilic, and thus tend to be transported actively across cell membranes rather than passively. Highly-specific transport systems utilizing folate receptors, the reduced folate carrier and the proton-coupled folate transporter mediate the passage of folates into the systemic tissues receptors. The anionic reduced folate carrier, which is found in all eukaryotic cells, delivers folates to systemic tissues at physiological pH (pH 7.4), whilst folate receptors transport folate via receptor-mediated at slightly acid and neutral pH (pH
Methotrexate can lower the concentration of folate in plasma, and thus may cause a megaloblastic anaemia. Other co-factors of tetrahydrofolate are responsible for metabolic reactions such amino acid interconversion (e.g., the conversion of homocysteine to methionine [a vitamin B12-dependent process] and the conversion of serine to glycine), histidine metabolism, formate generation and synthesis of essential purines. Folate molecules are highly hydrophilic, and thus tend to be transported actively across cell membranes rather than passively. Highly-specific transport systems utilizing folate receptors, the reduced folate carrier and the proton-coupled folate transporter mediate the passage of folates into the systemic tissues receptors. The anionic reduced folate carrier, which is found in all eukaryotic cells, delivers folates to systemic tissues at physiological pH (pH 7.4), whilst folate receptors transport folate via receptor-mediated at slightly acid and neutral pH (pH