019 The normal thyroid axis Flashcards
1
Q
Which selenodeionidase enzyme is found in liver, kidney and muscle?
A
D1
2
Q
Which selenodeionidase enzymes is found in brain, pituitarygland?
A
D2
3
Q
Which selenodeionidase enzyme formes inactive T3.
A
D3
4
Q
Which proteins are T3/T4 bound to?
A
Thyroid binding protein TBP
Transthyreitin
Albumin
5
Q
Which releasing hormones does T3/T4 suppress?
A
GnRH
TRH
6
Q
Which pathway does TSH take on GPCR on thyroid follicular cell?
A
Adenylate cyclase and PLC
7
Q
Which thyroid receptor do feedback mechanisms act upon and where?
A
Liver, pituitary, hypothalamus
TR-beta
8
Q
Explain mechanism of active repression of DNA in absence of T3?
A
- In absence of T3 ligand
- DNA bound to co-repressor NCor, SMRT, HDAC
- HDAC causes DNA to be bound to histone
9
Q
Explain active transcription of T3
A
- T3 binds to receptor
- Monomeric receptor dimerizes with RXR on TRE
- HDAC removed
- Opens chromatin for transcription
10
Q
Explain permissive transcription of T3?
A
Even without TR or RXR, causes gene transcription.
