Intracellular Hormones

Question 1

What type of hormones are intracellular

Where is the receptor found and in what form when inactive

Answer 1

• steroid

- free floating in cyto or nucleus and is a multimetic protein when inactive ( bound to HSP )

Question 2

What does the receptor-hormone complex do and its name

Answer 2

-transcription factor which regulates transcription of genes

Question 3

List and describe the domains of steroid hormone receptors

Answer 3

• N terminal has transcription factor binding domain to interact with other transcription factors and active transcription by interacting with other transcription machinery
• middle domain is DNA binding domain and binds to specific DNA sequence
• C terminal has ligand binding domain to bind to ligand

Question 4

What occurs when ligand bound to receptor

Where does receptor-ligand complex bind to

Answer 4

• conformational change occurs to receptor and HSP is displaced
• receptor now compotent to bind to DNA

-hormone response element( short DNA sequence near hormone response gene to be transcribed

Question 5

Describe mode of action of steroid hormones

Answer 5

• free hormone in plasma transferred to cells by transfer proteins
• lipid soluble hormone diffuses through phospholipid layer binding to receptor
• cellular response

( translocates into nucleus if found in cyto )

Question 6

Which are the best studied hormone receptors

Answer 6

-nuclear receptor subfamily 3

1 estrogen related receptor
2 estrogen receptor
3 3-ketosteroid receptor

Question 7

How does progesterone act as a chemoattractant spermatozoa

Answer 7

• progesterone modulates activity if CatSperm voltage gated Ca2 channels
• alters mobility

Question 8

Which g coupled receptor is a steroid receptor and its ligand

What do the binding proteins do to the DNA

Answer 8

• GPCR30
• estrogen

-distort backbone as they cause bending but don’t break the double bonds

Question 9

Describe the grooves of DNA in relation to binding by proteins

Answer 9

• major groove ( 12A wide and 8A deep). Proteins binds via a-helixes
• minor groove ( 5A wide and 8A deep ). To narrow to fit entire a helixes but has b-sheet structures of TATA box

Question 10

Example of Gq hormone and it’s major effect

Answer 10

• oxytocin

- increases Ca conc’s to stimulate muscle contraction