KA4b) Hydrophobic signals and control of transcription

What can hydrophobic signals do?

Diffuse directly through the phospholipid bilayer

What does hydrophobic signals bind to?

Intracellular receptors

Give an example of hydrophobic signal molecules

Steroid hormones; such as oestrogen and testosterone

What are the receptors for hydrophobic signals?

Transcription factors

What are transcription factors?

Proteins that when bound to DNA can either stimulate or inhibit transcription

Give an example of what stimulation without hormone looks like

No hormone means transcription factor doesn't bind; thus no transcription

Give an example of what stimulation with hormone looks like

Hormone binds to transcription factor and a complex binds to DNA; thus transcription takes place

What forms when the hormone binds to transcription factor?

Hormone receptor complex (HRC)

What is the hormone response element (HRE)?

When HRC binds to specific DNA sequences

How is the rate of transcription influenced?

By the binding of the HRC to the HRE; which can increase or decrease transcription