iron ion export across plasma membrane

Definition

Target type: biologicalprocess

The directed movement of iron ions from inside of a cell, across the plasma membrane and into the extracellular region. [GO_REF:0000074, GOC:BHF, GOC:kom, GOC:rl, GOC:TermGenie, PMID:15514116]

Iron ion export across the plasma membrane is a crucial process for maintaining cellular iron homeostasis. This complex process involves the coordinated action of several proteins, primarily **ferroportin (FPN)**, a transmembrane protein responsible for iron efflux.

**1. Iron Binding:** Iron ions (Fe2+) within the cell bind to **ferroportin**, a transmembrane protein located on the plasma membrane. The binding of iron to ferroportin is facilitated by the presence of histidine residues in the protein's structure.

**2. Oxidative Step:** Once bound to ferroportin, Fe2+ is oxidized to Fe3+ by the enzyme **hephaestin (Heph)**, a copper-containing ferroxidase. This oxidation step is essential for iron release from ferroportin and subsequent transport across the plasma membrane.

**3. Translocation:** The oxidized Fe3+ ions are then translocated across the plasma membrane via **ferroportin**. The exact mechanism of translocation is not fully understood, but it is likely to involve a conformational change in ferroportin, allowing the iron to pass through its transmembrane domain.

**4. Iron Binding to Transferrin:** Once outside the cell, Fe3+ ions bind to **transferrin**, a plasma protein responsible for iron transport in the bloodstream. Transferrin binds two iron atoms per molecule, forming a complex that delivers iron to cells throughout the body.

**5. Regulation of Iron Export:** The activity of ferroportin, and thus iron export, is tightly regulated. Several factors influence this regulation, including:

* **Hepcidin:** A small peptide hormone produced by the liver that binds to ferroportin, leading to its internalization and degradation. Hepcidin acts as a negative regulator of iron export.
* **Erythropoiesis:** During red blood cell production, the increased demand for iron leads to decreased hepcidin production, allowing for greater iron export.
* **Iron Status:** Iron levels in the body influence hepcidin production, with high iron levels leading to increased hepcidin production and reduced iron export.

**6. Importance of Iron Export:** The regulation of iron export is essential for maintaining iron homeostasis and preventing iron overload. Disruptions in iron export can lead to various health problems, including iron deficiency anemia (due to insufficient iron export) or iron overload disorders (due to excessive iron export).

In summary, iron ion export across the plasma membrane is a multi-step process involving multiple proteins, including ferroportin, hephaestin, and transferrin. This process is tightly regulated by factors such as hepcidin, erythropoiesis, and iron status. Proper regulation of iron export is crucial for maintaining iron homeostasis and overall health.'
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Proteins (1)

Compounds (3)