Steroid hormone receptors Flashcards
What is the purpose of carrier proteins?
To ensure that proteins are delivered to the entire body
What is the most important carrier protein for cortisol?
Transcortin
What is the most important carrier protein for thyroid hormone
Thyroxine-binding-globulin
What are the 3 structures that all hormone receptors contain?
Transcription-activating domain
DNA binding domain
Hormone-binding domain
How do steroid hormones activate receptors?
Hormone binds to hormone-binding site which releases inhibitory complex and exposes DNA binding site
How long will ligands remain in the bloodtsream until they’re secreted?
Hours due to binding with carrier proteins
After the hormone-receptor complex enters the nucleus, what else is needed to DNA transcription?
Transcription factors
What are primary response genes?
Jus, fos
First genes produced by binding of hormone-receptor complex
Negative feedback to cease transcription of primary genes
What are secondary genes?
Primary response genes turn on secondary response genes and initiate further rounds of transcription
What is aldosterone produced in response to?
Decrease in blood pressure
Can aldosterone be stored?
No
What is the receptor for aldosterone
Mineralocorticoid receptor
What is the carrier protein for aldosterone?
Transcortin, albumin
What does the kidney secrete in response to low blood pressure?
Renin
What is renin a precursor for?
Angiotensin I
Is Angiotensin I an active molecule?
No, angiotensin converting enzyme changes to Angiotensin II
What is the function of angiotensin II?
Increase vasoconstriction
Stimulates release of aldosterone
What enzyme changes renin to angiotensin I?
Angiotensinogen
What does an ACE inhibitor block? What is it used to treat?
Angiotensin converting enzyme
High blood pressure
If aldosterone causes the transcription of genes that code for an increase in sodium channels, are sodium channels primary or secondary response genes?
Secondary
What hormone does the thyroid gland produce?
Thyroxine (T4)
Is thyroxine an active hormone?
No, it is de-iodinized to make T3
What stimulates production of T3?
Cold and stress
What are the carrier proteins for Thyroxine?
Thyroxine-binding prealbumin
Thyroxine-binding globulin
What is the function of T3?
Increased metabolism, fat and protein mobilization, thermogenesis
What is the function of Thyrotropin releasing hormone?
Hypothalamus releases TRH to stimulate pituitary gland to produce TSH
What is the function of Thyrotropin stimulating hormone?
Stimulates the thyroid gland to produce T4
Dos the thyroid gland produce T3?
Yes, but the majority is T4
Where is T4 transformed in to T3?
Kidney & Liver
How does TRH reach the pituitary gland? What kind of signaling is this?
Via bloodstream
Endocrine
What other function does T4 have than producing T3?
Feedback inhibition on pituitary gland to stop TSH release
What are signs of feline hyperthyroidism
Thin despite good appetite Rapid heart rate Excitability Vomiting Thin hair
What causes feline hyperhtyroidism?
Thyroid adenoma
What are the treatments of feline hyperthyroidsm?
Methimazole
Gland removal
Radio-iodine
How does methimzaole treat hyperthyroidism?
Prevents T3/T4 production
What is the most common phosphate donor?
ATP
Which amino acid side chains can be phosphorylated?
Serine
Threonine
Tyrosine
Which enzyme is the catalyst for phosphrylation?
Kinase
Which enzyme takes off a phosphate group?
Phosphotase
How does adding a phosphate activate a protein?
Usually exposes binding site by changing conformation
