Iron and Heme Flashcards
What two molecules can iron be bound to during storage?
hemosiderin and ferritin
What is the protein that transports iron in the blood?
transferrin
What part of the GI tract is iron absorbed in?
duodenum
What enzyme in the GI tract can reduce iron from Fe3+ to Fe2+?
Cyt p450
What GI protein is responsible for releasing iron into the plasma?
Ferroportin
Which protein inhibits ferroportin?
hepcidin
What protein transports iron out of the endosome and into the cell?
DMT1
What protein does ferritin form when it misfolds and degenerates?
hemosiderin
At what level is ferritin production regulated?
post-transcriptional
Do iron regulatory proteins bind to the 5’ UTR of ferritin in the presence of absence of iron?
absence
What does the presence of iron do to the IRPs?
inhibits their inhibition of iron processing
What does free iron do to ALA synthase levels?
increase
What does free iron do to transferrin receptor levels?
decreases transferrin receptor levels
What percent saturation is transferrin typically?
1/3
What is the best measure for serum iron stores?
serum ferritin
Which interleukin stimulates the synthesis of hepcidin?
IL-6
Absence of what enzyme cause Acute Intermittent Porphyria?
PBG Deaminase
Absence of what enzyme causes Porphyria Cutanea Tarda?
UPG Decarboxylase
What two enzymes of heme synthesis does lead inhibit?
Ferrochelatase and ALA Dehydratase
What organelle is ALA Synthase located? Why?
Mitochondria
availability of succinyl-CoA from citric acid cycle
What two enzymes of heme synthesis are located in the mitochondria?
ALA Synthase
Ferrochelatase
What is the main inhibitory molecule of ALA synthase?
heme
What commonly leads to a porphyria?
alcohol consumption
What two products accumulate during Acute Intermittent Porphyria?
ALA and PBG
What is more common, AIP or PCT?
PCT
How is PCT diagnosed?
urine will fluoresce under UV light
What substance accumulates during lead poisoning?
ALA
The iron response element is found on what three proteins?
ferritin
ALA synthase
ferritin receptor
What protein can reduce iron on the luminal side of enterocytes?
Cytochrome B
What is the oxidation state of iron bound to transferrin?
Fe3+
What two locations will iron be stored in during ACD?
RES macrophages
enterocytes
Hereditary hematochromatosis can be traced back to what gene? increase or decrease?
hepcidin
decrease
What two products accumulate during AIP?
PBG and ALA
What does TIBC specifically measure?
transferrin saturation
Transferrin saturation below what percent points to iron deficiency?
15%
Is hepcidin expression increased or decreased during hematochromatosis?
decreased
What does Fe3+ do to heme synthesis?
repress
What does hemin do to heme synthesis?
repress
How is AIP diagnosed?
dark red urine
Durig iron overload, what is the first cell to express hemosiderin?
macrophages
