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Human iron homeostasis is regulated at two different levels. Systemic iron levels are balanced by the controlled absorption of dietary iron by enterocytes, the cells that line the interior of the intestines, and the uncontrolled loss of iron from epithelial sloughing, sweat, injuries and blood loss. In addition, systemic iron is continuously ...
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.
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.
Iron is also stored as a pigment called hemosiderin, which is an ill-defined deposit of protein and iron, created by macrophages where excess iron is present, either locally or systemically, e.g., among people with iron overload due to frequent blood cell destruction and the necessary transfusions their condition calls for. If systemic iron ...
Crystal structure of iron regulatory protein 1 in complex with ferritin H IRE-RNA, Protein Data Bank entry 2IPY. [1]In molecular biology, the iron response element or iron-responsive element (IRE) is a short conserved stem-loop which is bound by iron response proteins (IRPs, also named IRE-BP or IRBP).
It is the primary intracellular iron-storage protein in both prokaryotes and eukaryotes, keeping iron in a soluble and non-toxic form. In humans, it acts as a buffer against iron deficiency and iron overload. [3] Ferritin is found in most tissues as a cytosolic protein, but small amounts are secreted into the serum where it functions as an iron ...
It is thought that this protein functions to regulate circulating iron uptake by regulating the interaction of the transferrin receptor with transferrin. [6] The HFE gene contains 7 exons spanning 12 kb. [7] The full-length transcript represents 6 exons. [8] HFE protein is composed of 343 amino acids. There are several components, in sequence ...
Thus, transferrin receptor maintains cellular iron homeostasis. TfR production in the cell is regulated according to iron levels by iron-responsive element-binding proteins, IRP1 and IRP2. In the absence of iron, one of these proteins (generally IRP2) binds to the hairpin like structure that is in the 3' UTR of the TfR mRNA. Once binding occurs ...