CH8 Iron Uptake & Recycling

Which RECEPTOR on cells BINDS to TRANSFERRIN?

Transferrin receptor 1 (TfR1)

Once transferrin binds to the TfR1, how is it taken up into the cell?

The cell will ENGULF/invaginate, creating an ENDOSOME (vescicle)

What happens inside of the ENDOSOME that releases Fe3+ from transferrin?

pH CHANGES becoming more ACIDIC

Which Transporter transports Iron out of the endosome and into the cytoplasm of the cell?

DMT-1

Divalent Metal Transporter-1

Then the endosome returns to the membrane

Which cells are involved in Iron STORAGE?

ALL CELLS except RBCs

Macrophages & hepatocytes

What is APOferritin?

Ferritin WITHOUT any FERRIC iron bound

What is Ferritin?

The storage form of Iron, FERRIC IRON bound to apoferritin

How many Iron ions can ONE apoferritin bind?

>4000 iron ions

What is Hemosiderin?

PARTIALLY DEGRADED form of ferritin

What happens with TfR1 activity when Iron is LOW

LOW Iron = HIGH TfR1

What happens with TfR1 activity when Iron is HIGH

HIGH iron = LOW TfR1

Which cells recycle iron from OLD RBCs?

MACROPHAGES in the SPLEEN

How is Iron stored in the Macrophages?

Ferritin

What do haptoglobin/hemopexin salvage?

Hemoglobin/heme

Which type of dietary iron is absorbed more efficiently?

HEME-iron