Lecture 13

Question 1

What are the 2 forms of non-haem iron?

Answer 1

Ferrous (2+) and Ferric (3+)

Question 2

How does iron move around the blood?

Answer 2

Bound to transferrin

Question 3

Describe the start of the haem iron absorption.

Answer 3

Haem iron is released from protein by digestion and enters cells via an unknown mechanism. It is broken down by haem oxygenase to release biliverdin and Fe2+.

Question 4

Describe the start of the non-haem absorption.

Answer 4

Fe3+ is insoluble so is converted to Fe2+ by ferric reductase Dcytb or by dietary components such as vitamin C. DMT1 transports Fe2+ into the cell.

Question 5

What hormone indicates high iron levels?

Answer 5

Hepcidin

Question 6

What protein stores iron inside the enterocyte?

Answer 6

Ferritin

Question 7

What protein moves iron across the cytosol?

Answer 7

Mobilferrin

Question 8

What is the basolateral exporter of Fe2+?

Answer 8

IREG1

Question 9

What oxidises Fe2+ into Fe3+ at the BLM?

Answer 9

Hephaestin ferroxidase

Question 10

What is DMT1

Answer 10

H+ coupled transporter of divalent metals

Question 11

Defective DMT1 causes what?

Answer 11

Microcytic anaemia

Question 12

At what stage of red blood cell development is haemoglobin made?

Answer 12

Between the polychromatous and orthochromatic erythroblast stage

Question 13

What enzyme is responsible for adding Fe2+ to protiphorin to make haem?

Answer 13

Ferrochelatase

Question 14

How many molecules of Fe3+ bind to transferrin?

Answer 14

2

Question 15

What activity acidifies the inside of endosomes containing DMT1 and Fe3+/transferrin

Answer 15

H+/ATPase

Question 16

What causes the Fe3+ inside the endosome to dissociate from transferrin and turn to Fe2+?

Answer 16

The low pH

Question 17

How does the Fe2+ exit the endosome?

Answer 17

Via DMT1 driven by the outward proton gradient.

Question 18

In iron deficiency, what is upregulated?

Answer 18

IREG1

Question 19

Describe how IREG1 can be upregulated in iron deficiency

Answer 19

It has an iron response element in the 5’ end.