A steroid hydroxylase is a class of hydroxylase enzymes involved in the biosynthesis of steroids. [1] [2]
A steroid hydroxylase is a class of hydroxylase enzymes involved in the biosynthesis of steroids. [1] [2]
The adrenal glands are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which produces steroid hormones and an inner medulla. The adrenal cortex itself is divided into three main zones: the zona glomerulosa, the zona fasciculata and the zona reticularis.
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy.
Adrenocorticotropic hormone is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress. Its principal effects are increased production and release of cortisol and androgens by the cortex and medulla of the adrenal gland, respectively. ACTH is also related to the circadian rhythm in many organisms.
The adrenal cortex is the outer region and also the largest part of an adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. It is also a secondary site of androgen synthesis.
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a central role in the homeostatic regulation of blood pressure, plasma sodium (Na+), and potassium (K+) levels. It does so primarily by acting on the mineralocorticoid receptors in the distal tubules and collecting ducts of the nephron. It influences the reabsorption of sodium and excretion of potassium (from and into the tubular fluids, respectively) of the kidney, thereby indirectly influencing water retention or loss, blood pressure, and blood volume. When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and kidney disease. Aldosterone has exactly the opposite function of the atrial natriuretic hormone secreted by the heart.
Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders characterized by impaired cortisol synthesis. It results from the deficiency of one of the five enzymes required for the synthesis of cortisol in the adrenal cortex. Most of these disorders involve excessive or deficient production of hormones such as glucocorticoids, mineralocorticoids, or sex steroids, and can alter development of primary or secondary sex characteristics in some affected infants, children, or adults. It is one of the most common autosomal recessive disorders in humans.
A hormone receptor is a receptor molecule that binds to a specific chemical messenger. Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other receptors for various ligands, such as fatty acids and prostaglandins. Hormone receptors are of mainly two classes. Receptors for peptide hormones tend to be cell surface receptors built into the plasma membrane of cells and are thus referred to as trans membrane receptors. An example of this is Actrapid. Receptors for steroid hormones are usually found within the protoplasm and are referred to as intracellular or nuclear receptors, such as testosterone. Upon hormone binding, the receptor can initiate multiple signaling pathways, which ultimately leads to changes in the behavior of the target cells.
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones.
Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia resulting from a defect in the gene CYP17A1, which encodes for the enzyme 17α-hydroxylase. It causes decreased synthesis of cortisol and sex steroids, with resulting increase in mineralocorticoid production. Thus, common symptoms include mild hypocortisolism, ambiguous genitalia in genetic males or failure of the ovaries to function at puberty in genetic females, and hypokalemic hypertension (respectively). However, partial (incomplete) deficiency is notable for having inconsistent symptoms between patients, and affected genetic (XX) females may be wholly asymptomatic except for infertility.
17α-Hydroxyprogesterone (17α-OHP), also known as 17-OH progesterone (17-OHP), or hydroxyprogesterone (OHP), is an endogenous progestogen steroid hormone related to progesterone. It is also a chemical intermediate in the biosynthesis of many other endogenous steroids, including androgens, estrogens, glucocorticoids, and mineralocorticoids, as well as neurosteroids.
Aldosterone synthase, also called steroid 18-hydroxylase, corticosterone 18-monooxygenase or P450C18, is a steroid hydroxylase cytochrome P450 enzyme involved in the biosynthesis of the mineralocorticoid aldosterone and other steroids. The enzyme catalyzes sequential hydroxylations of the steroid angular methyl group at C18 after initial 11β-hydroxylation. It is encoded by the CYP11B2 gene in humans.
Cholesterol side-chain cleavage enzyme is commonly referred to as P450scc, where "scc" is an acronym for side-chain cleavage. P450scc is a mitochondrial enzyme that catalyzes conversion of cholesterol to pregnenolone. This is the first reaction in the process of steroidogenesis in all mammalian tissues that specialize in the production of various steroid hormones.
Cholesterol 7 alpha-hydroxylase also known as cholesterol 7-alpha-monooxygenase or cytochrome P450 7A1 (CYP7A1) is an enzyme that in humans is encoded by the CYP7A1 gene which has an important role in cholesterol metabolism. It is a cytochrome P450 enzyme, which belongs to the oxidoreductase class, and converts cholesterol to 7-alpha-hydroxycholesterol, the first and rate limiting step in bile acid synthesis.
Steroid 21-hydroxylase is an enzyme that hydroxylates steroids at the C21 position and is involved in biosynthesis of aldosterone and cortisol. The enzyme converts progesterone and 17α-hydroxyprogesterone into 11-deoxycorticosterone and 11-deoxycortisol, respectively, within metabolic pathways that ultimately lead to aldosterone and cortisol. Deficiency in the enzyme may cause congenital adrenal hyperplasia.
Steroid 11β-hydroxylase, also known as steroid 11β-monooxygenase, is a steroid hydroxylase found in the zona glomerulosa and zona fasciculata of the adrenal cortex. Named officially the cytochrome P450 11B1, mitochondrial, it is a protein that in humans is encoded by the CYP11B1 gene. The enzyme is involved in the biosynthesis of adrenal corticosteroids by catalyzing the addition of hydroxyl groups during oxidation reactions.
25-hydroxycholesterol 7-alpha-hydroxylase also known as oxysterol and steroid 7-alpha-hydroxylase is an enzyme that in humans is encoded by the CYP7B1 gene. This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids.
The halloween genes are a set of genes identified in Drosophila melanogaster that influence embryonic development. All of the genes code for cytochrome P450 enzymes in the ecdysteroidogenic pathway (biosynthesis of ecdysone from cholesterol). Ecdysteroids such as 20-hydroxyecdysone and ecdysone influence many of the morphological, physiological, biochemical changes that occur during molting in insects.
A steroidogenesis inhibitor, also known as a steroid biosynthesis inhibitor, is a type of drug which inhibits one or more of the enzymes that are involved in the process of steroidogenesis, the biosynthesis of endogenous steroids and steroid hormones. They may inhibit the production of cholesterol and other sterols, sex steroids such as androgens, estrogens, and progestogens, corticosteroids such as glucocorticoids and mineralocorticoids, and neurosteroids. They are used in the treatment of a variety of medical conditions that depend on endogenous steroids.
A prohormone is a committed precursor of a hormone consisting of peptide hormones synthesized together that has a minimal hormonal effect by itself because of its expression-suppressing structure, often created by protein folding and binding additional peptide chains to certain ends, that makes hormone receptor binding sites located on its peptide hormone chain segments inaccessible. Prohormones can travel the blood stream as a hormone in an inactivated form, ready to be activated later in the cell by post-translational modification.
Steroidogenic enzymes are enzymes that are involved in steroidogenesis and steroid biosynthesis. They are responsible for the biosynthesis of the steroid hormones, including sex steroids and corticosteroids, as well as neurosteroids, from cholesterol. Steroidogenic enzymes are most highly expressed in classical steroidogenic tissues, such as the testis, ovary, and adrenal cortex, but are also present in other tissues in the body.
