Steroid Biosynthesis Flashcards
How many IPP molecules does vitamin D contain
6
The rate limiting step of steroid hormone synthesis is catalyzed by what enzyme?
Desmolase
Desmolase catalyzes the formation of what?
Pregnenolone
What enhances/stimulates desmolase activity?
ACTH
By itself what can Pregnenolone effect?
NMDA glutamate receptor (memory and learning)
For synthesis of other progesterones, Pregnenolone must be converted to what?
Progesterone
Enzyme that catalyzes Pregnenolone to progesterone?
17-alpha-hydroxylase
3-beta-hydroxysteroid dehydrogenase
What type of steroid hormones affect sodium/water levels in tissues?
Mineralocorticoids
What type of steroid hormones have affinity for Mineralocorticoid receptors but are 100 times more concentrated than Mineralocorticoids?
Glucocorticoids
What type of steroid hormones are performance enhancing drugs (PEGs)?
Androgens
Where is aldosterone made?
Zona Glomerulosa
Where is cortisol made?
Zona fasciculata
Where are steroid hormone synthesized?
ER of adrenal cortex, ovaries, and testes
FSH stimulates estero dial production in ovaries by activating what enzyme?
Aromatase
Defect in this leads to salt wasting (hyponatremia) and hypotension due to decreased production of aldosterone, and hypoglycemia due to decreased production of cortisol.
In females, this deficiency causes VIRILISM (development of male secondary chacteristics) due to an increased flow of intermediates into adrenal androgens.
21-hydroxylase
Deficiency in this enzyme causes a loss of cortisol as well as sex steroids.
However, the decrease in cortisol is compensated for by increased production of corticosterone
17-alpha-hydroxylase
Defect in this enzyme causes hypertension due to accumulation of 11-decoxycorticosterone, which has Mineralocorticoid activity
11-beta-hydroxylase
Excessive levels of aldosterone leads to this disorder which causes increase blood volume and hypertension
Conn syndrome
Elevated cortisol levels are associated with this disorder and are marked by the accumulation of fat on the face and trunk
Cushing syndrome
Cortisol levels can be controlled so that they do not signal to the receptors for Mineralocorticoids by what enzyme that converts it to cortisONE?
11beta-hydroxysteroid dehydrogenase
Enzyme for testosterone to dihydrotestosterone
5alpha-reductase
What drug inhibits 5alpha - redcuctase and can be used to treat benign prostatic hyperplasia or male pattern baldness
Finasteride
What is the active form of vitamin D
Calcitriol
What do we get vitamin D3 from in the intestinal cells?
Ergocalciferol (vit D2)
Enzyme in Liver that converts cholecalciferol (D3) to 25-hydroxycholecalciferol?
25-hydroxylase
Enzyme in KIDNEY for 25-hydroxycholecalciferol to 1,25 dihydroxycholecalciferol (Calcitriol)
1 - alpha-hydroxylase
