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Human iron metabolism is the set of chemical reactions that maintain human homeostasis of iron at the systemic and cellular level. Iron is both necessary to the body and potentially toxic. Controlling iron levels in the body is a critically important part of many aspects of human health and disease.
In human cells, the best-characterized iron-sensing mechanism is the result of post-transcriptional regulation of mRNA (the chemical instructions derived from DNA genes to make proteins). Sequences of mRNA called iron-responsive elements (IREs) are contained within the mRNA sequences that code for transferrin receptors and for ferritin.
The amino acids which bind the iron ion to the transferrin are identical for both lobes; two tyrosines, one histidine, and one aspartic acid. For the iron ion to bind, an anion is required, preferably carbonate (CO 2− 3). [18] [13] Transferrin also has a transferrin iron-bound receptor; it is a disulfide-linked homodimer. [16]
Serum iron is a medical laboratory test that measures the amount of circulating iron that is bound to transferrin and freely circulate in the blood. Clinicians order this laboratory test when they are concerned about iron deficiency, which can cause anemia and other problems. 65% of the iron in the body is bound up in hemoglobin molecules in red blood cells.
Hepcidin is a protein that in humans is encoded by the HAMP gene. Hepcidin is a key regulator of the entry of iron into the circulation in mammals. [6]During conditions in which the hepcidin level is abnormally high, such as inflammation, serum iron falls due to iron trapping within macrophages and liver cells and decreased gut iron absorption.
Transferrin (mg/dL) = 0.8 x TIBC (μg of iron/dL) – 43; Transferrin (mg/dL) = 0.7 x TIBC (μg of iron/dL) To measure TIBC in the blood is less expensive than a direct measurement of transferrin. [4] [5] The TIBC should not be confused with the unsaturated iron-binding capacity or UIBC (LOINC 2501-5, 22753-8 & 35216-1). The UIBC is calculated ...
The existence of a receptor for transferrin iron uptake has been recognized since the late 1950s. [2] Earlier two transferrin receptors in humans, transferrin receptor 1 and transferrin receptor 2 had been characterized and until recently cellular iron uptake was believed to occur chiefly via these two well documented transferrin receptors ...
Transferrin receptor 2 (TfR2) is a protein that in humans is encoded by the TFR2 gene. [ 5 ] [ 6 ] This protein is involved in the uptake of transferrin -bound iron into cells by endocytosis , although its role is minor compared to transferrin receptor 1 .