Iron-responsive element-binding protein

Iron-responsive element-binding protein (IRE-BP) is a type of protein that plays a crucial role in the regulation of iron metabolism in cells. It is also known as Iron Regulatory Protein (IRP). The primary function of IRE-BP is to control the translation and stability of mRNAs that encode for proteins involved in iron storage, transport, and utilization. This regulation ensures that iron levels within the cell remain within a healthy range, preventing either iron deficiency or toxicity.

Function

IRE-BP binds to iron-responsive elements (IREs), which are specific sequences of nucleotides found in the mRNA of genes involved in iron metabolism. The binding of IRE-BP to IREs can either inhibit or enhance the translation of the mRNA, depending on the cellular context and the specific mRNA involved. For example, in conditions of iron deficiency, IRE-BP binds to the IREs located in the 5' untranslated region (UTR) of the ferritin mRNA, inhibiting its translation and thus decreasing iron storage. Conversely, it binds to the IREs in the 3' UTR of the transferrin receptor mRNA, stabilizing the mRNA and increasing the production of transferrin receptors to enhance iron uptake.

Structure

IRE-BP exists in two forms: an active, iron-free form (apo-IRE-BP) that can bind to IREs, and an inactive, iron-bound form (holo-IRE-BP) that cannot. The transition between these two forms is regulated by the iron status of the cell. The protein structure of IRE-BP includes a specific domain that senses iron levels, undergoing conformational changes that either promote or inhibit its binding to IREs.

Clinical Significance

Alterations in the function of IRE-BP can lead to disorders of iron metabolism, such as anemia or hemochromatosis. Understanding the mechanisms of IRE-BP action has implications for the development of therapeutic strategies for these conditions. For instance, targeting the IRE-BP/IRE interaction could be a strategy to modulate iron levels in diseases characterized by iron imbalance.

Research

Research on IRE-BP continues to uncover its roles not only in iron metabolism but also in other cellular processes, including oxidative stress response, cell proliferation, and apoptosis. Studies are also exploring the potential of IRE-BP as a target for the treatment of diseases beyond those directly related to iron metabolism.