Hormona esteroide: Diferenzas entre revisións

== Efectos ==

 

 

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. This is in contrast to the actions of non-steroid hormones, which are water-soluble typically peptide hormones, acting through membrane bound receptors and intracellular second messenger systems to exert their effects. 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 [[protein dimer|dimer]]ize: 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.<ref name=gup/><ref>{{cite journal| author= Moore FL, Evans SJ |title= Steroid hormones use non-genomic mechanisms to control brain functions and behaviors: a review of evidence |year = 1995|url= | journal= Brain Behav Evol | volume= 51 | issue= 4 |pages = 41–50 |pmid= 10516403 }}</ref><ref>{{cite journal| author= Marcinkowska E, Wiedłocha A |title=Steroid signal transduction activated at the cell membrane: from plants to animals |year = 2002|url= | journal= Acta Biochim Pol | volume= 43 | issue= 9 |pages = 735–745 |pmid= 12422243 }}</ref><ref>{{cite journal| author= Rousseau GG |title= Fifty years ago: The quest for steroid hormone receptors |year = 2013 |url= | journal= Mol Cell Endocrinol | volume= 375 | issue=1–2 |pages = 10–13 |pmid= 23684885 |doi=10.1016/j.mce.2013.05.005}}</ref>