Steroid hormone 328579 221985511 2008-06-27T00:23:43Z 124.170.214.52 [[WP:UNDO|Undid]] revision 221964601 by [[Special:Contributions/204.102.107.107|204.102.107.107]] ([[User talk:204.102.107.107|talk]]) {{Unreferenced|date=December 2007}} '''Steroid hormones''' are [[steroid]]s which act as [[hormone]]s. Mammalian steroid hormones can be grouped into five groups by the [[receptor (biochemistry)|receptor]]s to which they bind: [[glucocorticoid]]s, [[mineralocorticoid]]s, [[androgen]]s, [[estrogen]]s, and [[progestagen]]s. [[Vitamin D]] derivatives are a sixth closely related hormone system with homologous receptors, though technically [[sterol]]s rather than steroids. == Overview == The natural steroid hormones are generally synthesized from [[cholesterol]] in the [[gonad]]s and [[adrenal gland]]s. These forms of hormones are lipids. They can enter the cell membrane quite easily and enter right into the nuclei. Steroid hormones are generally carried in the blood bound to specific carrier [[protein]]s such as sex hormone binding globulin or corticosteroid binding globulin. Further conversions and catabolism occurs in the liver, other "peripheral" tissues, and in the target tissues. Because steroids and sterols are [[lipid]] soluble, they can [[diffusion|diffuse]] fairly freely from the blood through the [[cell membrane]] and into the [[cytoplasm]] of target cells. In the cytoplasm the steroid may or may not undergo an [[enzyme]]-mediated alteration such as reduction, hydroxylation, or aromatization. In the cytoplasm, the steroid binds to the specific receptor, a large metalloprotein. Upon steroid binding, many kinds of steroid receptor [[dimer|dimerize]]: two receptor subunits join together to form one functional [[DNA]]-binding unit that can enter the [[cell nucleus]]. In some of the hormone systems known, the receptor is associated with a [[heat shock protein]] which is released on the binding of the [[ligand]], the hormone. Once in the nucleus, the steroid-receptor ligand complex binds to specific [[DNA]] sequences and induces transcription of its target [[gene]]s. == Synthesis == [[Image:Steroidfromcholesterol.PNG|frame|none|Steroids made from Cholesterol|100px]] == Synthetic steroids and sterols == A variety of synthetic steroids and sterols have also been contrived. Most are steroids but some non-steroidal molecules can interact with the steroid receptors because of a similarity of shape. Some synthetic steroids are weaker, some much stronger, than the natural steroids whose receptors they activate. Some examples of synthetic steroid hormones: * Glucocorticoids: [[prednisone]], [[dexamethasone]], [[triamcinolone]] * Mineralocorticoid: [[fludrocortisone]] * Vitamin D: [[dihydrotachysterol]] * Androgens: [[oxandrolone]], [[nandrolone]] (also known as [[anabolic steroid]]s) * Estrogens: [[diethylstilbestrol]] (DES) * Progestins: [[norethindrone]], [[medroxyprogesterone acetate]] == External links == * Steroidogenic enzymes: [http://science.co.il/hi/pub/1992-JSBMB-43-779.asp Review on structure, function, and role in regulation of steroid hormone biosynthesis] {{Hormones}} [[Category:Steroid hormones| ]] [[de:Steroidhormon]] [[fr:Hormone stéroïde]] [[nl:Steroïdhormoon]] [[ja:ステロイドホルモン]] [[no:Steroidhormon]] [[pl:Hormony steroidowe]] [[ru:Стероидные гормоны]] [[sv:Steroidhormon]] [[tr:Steroid hormon]] [[zh:類固醇激素]]