Steroid Hormone Biochemistry

  1. Main enzyme involved in cholesterol conversion to steroid hormone is:
    • Cholesterol sidechain cleaving enzyme aka cholesterol desmolase
    • Catalyzes the first step in steroid hormone biosynthesis
  2. Where does steroid biosynthesis take place? (within the cell)
    In the inner mitochondrial membrane
  3. Which protein moves cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane?
    Steroidogenic acute regulatory protein (StAR)
  4. What is StAR?
    Steroidogenic acute regulatory protein, which omves cholesterol form outer mitochondrial membrane to the inner mitochondrial membrane
  5. T/F: cholesterol desmolase is the first enzyme involved in steroid hormone biosynthesis and this occurs in the outer mitochondrial membrane
    False; desmolase is the first enzyme involved in the pathway, however, it occurs in the inner mitochondrial membrane, not in the outer.
  6. Protein and enzyme involved in the first step of steroid hormone biosynthesis:
    • Cholesterol desmolase
    • Steroidogenic acute regulatory protein
  7. Cholesterol desmolase (aka cholesterol sidechain cleaving enzyme), converts cholesterol into______
  8. Cholesterol desmolase (aka cholesterol sidechain cleaving enzyme) is expressed from gene ______, and cleaves carbon _____
    • CYP11A
    • 20
  9. T/F: CYP450 oxidize many different compounds including cholesterol
  10. Cholesterol has ____ carbons, progestogens, mineralocorticoids and glucocorticoid have ____ carbons, androgens with ____ carbons and estrogen _____ carbons
    • 27
    • 21
    • 19
    • 18
  11. 21-hydroxylase deficiency will cause abnormality in which electrolyte?
    Na+, this will cause salt wasting because of deficiency in mineralocorticoids which would lead to inadequate regulation of salt and excessive sodium will be lost in urine
  12. 21-hydroxylase deficiency will in turn lead to increased in _____ and _____
    • Progesterone (just upstream of mineralocorticoids synthesis)
    • Androgen
  13. T/F: Androgen is made via the 17’s and mineralocorticoid and glucocorticoid are made via the 21’s
  14. 21-hydroxylase deficiency, will have deficiency in _____ and ____
    • Aldosterone
    • Cortisol
  15. ____ link an alcohol at C21, _____ lyses the bond between C17-C20, ______ forms aromatic ring by oxidizing
    • 21-hydroxylase
    • 17-20 lyase
    • Aromatase
  16. Micropenis, ambiguous genitalia, gynecomastia can be seen in males who lack ___
    • 3 beta dehydrogenase (causes virilization in males)
    • (21 hydroxylase deficiency can cause excessive virilization)
Card Set
Steroid Hormone Biochemistry
Endo Exam 2