Steroid Receptors

Question 1

What are the three types of steroid hormones?

Answer 1

• glucocorticoids
• mineralocorticoids
• sex steroids

Question 2

What are the two hormones involved in the release of cortisol?

Answer 2

• corticotrophin releasing hormone

- adrenocorticotrophic hormone

Question 3

Where is cortisol produced?

Answer 3

Adrenal cortex

Question 4

Release of adrenocorticotrophic hormone

Answer 4

• CRG binds to receptor
• activates G protein
• produces cAMP
• PKA phosphorylates and activates Ca2+ channels
• Ca2+ binds to synaptotagmin

Question 5

Effect of ACTH

Answer 5

• receptor is a GPCR linked to Gs
• produces cAMP
• activates PKA
• PKA phosphorylates enzymes involved in the synthesis of cortisol and increases synthesis of these enzymes

Question 6

How does ACTH alter the production of enzymes?

Answer 6

• translocates to the nucleus
• phosphorykates CRE-binding protein (CREB)
• CREB binds to cAMP response element (CRE)
• activates gene transcription

Question 7

How does cortisol work?

Answer 7

• steroid receptor is bound to chaperone receptor
• heat shock protein 90 (HSP90) is the main steroid receptor binding protein
• binding of cortisol to the glucocorticoid receptors causes translocation to the nucleus and HSP90 is released
• active receptor undergoes diamerization to form a homodiamer
• receptor-cortisol complex binds to DNA at glucocorticoid response elements (GRE)
• activates RNA polymerase
• gene transcription