Steroid Hormone Metabolism 1 Flashcards
Name few androgens
Testosterone, dehydroepiandrosterone (DHEA), dihydrotestosterone.
Name a few estrogens.
17-Beta-estradiol and progesterone
Name the hormone that is required for embryo implantation.
Progesterone mainly (little help from estrogen)
What are the functions of DHEA?
It is a weak androgen that can be converted into a more potent androgen (estrogen) in extra-adrenal tissues. In postmenopausal women, DHEA is an important precursor of estorgen. It inhibits G6P dehydrogenase, regulates NAD+ coenzymes.
What are the functions of aldosterone and cortisol?
Cortisol functions to increase blood glucose through gluconeogenesis (stimulates gluconeogenesis in liver, protein degradation in muscle and mobilization of fatty acids from adipose tissue). Aldosterone raises blood pressure and fluid volume by retaining Na+ and
excreting K
What is the role of StAR?
StAR (steroidogenic acute regulatory protein) is a hormone-induced transport protein factor that mediates acute regulation of steroid hormone biosynthesis.
What is the rate-limiting step in steroid biosynthesis?
The side chain cleavage of cholesterol (C-27) into pregnenolone (C-21) and C-6 isocaproaldehyde. This reaction is catalyzed by desmolase or 20-22 lyase.
What is the role of 5-alpha-reductase?
5-alpha-reductase is the enzyme that converts testosterone into DHT. This enzyme is located in the ER.
Name the enzvme that converts testosterone into estradiol.
Testosterone is converted into estradiol from aromatase in leydig cells or via DHEA in follicular cells and mammary glands.
Name the organ in which aldosterone and cortisol are produced.
The adrenal gland.
Name the most common enzyme in steroid biosynthesis (generic is OK).
P450-hydroxylases are the most common enzyme in steroid biosynthesis.
Conversion of cholesterol into pregnenolone occurs in _______________.
Mitochondria
