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Folate is required for the body to make DNA and RNA and metabolise amino acids necessary for cell division and maturation of blood cells. [1] [8] As the human body cannot make folate, it is required in the diet, making it an essential nutrient. [9] It occurs naturally in many foods.
Folate deficiency, also known as vitamin B 9 deficiency, is a low level of folate and derivatives in the body. [1] This may result in megaloblastic anemia in which red blood cells become abnormally large, and folate deficiency anemia is the term given for this medical condition. [3] Signs of folate deficiency are often subtle. [4]
Aluminium, the third most common element in the Earth's crust (after oxygen and silicon), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body. [38] Transferrins can bind aluminium. [39]
A functional coordination between these 2 mechanisms has been proposed to be the method of folate uptake in certain cell types. Methotrexate (MTX) is an antifolate chemotherapeutic agent that is actively transported by the carrier-mediated uptake system. RFC1 plays a role in maintaining intracellular concentrations of folate. [6]
Folate acts as a co-enzyme in the form of tetrahydrofolate (THF), which is involved in the transfer of single-carbon units in the metabolism of nucleic acids and amino acids. THF is involved in purine and pyrimidine nucleotide synthesis, so is needed for normal cell division, especially during pregnancy and infancy, which are times of rapid growth.
Because of this property, eumelanin is thought to protect skin cells from sunlight's Ultraviolet A (UVA) and Ultraviolet B (UVB) radiation damage, reducing the risk of skin tissue folate depletion, preventing premature skin aging and reducing the risks of sunburn and skin cancer. [49] Melanin inhibits UVB-powered vitamin D synthesis in the skin.
PCFT-mediated transport into cells is optimal at pH 5.5. The low-pH activity and the structural specificity of PCFT (high affinity for folic acid, and low affinity for PT523 - a non-polyglutamable analog of aminopterin) distinguishes this transporter functionally from the other major folate transporter, the reduced folate carrier [15] (optimal activity at pH 7.4, very low affinity for folic ...
Folate receptors bind folate and reduced folic acid derivatives and mediates delivery of tetrahydrofolate to the interior of cells. [1] It is then converted from monoglutamate to polyglutamate forms - such as 5-methyltetrahydrofolate - as only monoglutamate forms can be transported across cell membranes. Polyglutamate forms are biologically ...