Effects
Steroids exert a wide variety of effects mediated by slow genomic as well as by rapid nongenomic mechanisms. They bind to nuclear receptors in the cell nucleus for genomic actions. Membrane-associated steroid receptors activate intracellular signaling cascades involved in nongenomic actions.
Because steroids and sterols are lipid-soluble, they can 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 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 genes.
Read more about this topic: Steroid Hormone
Famous quotes containing the word effects:
“The ultimate result of shielding men from the effects of folly, is to fill the world with fools.”
—Herbert Spencer (1820–1903)
“Each of us, even the lowliest and most insignificant among us, was uprooted from his innermost existence by the almost constant volcanic upheavals visited upon our European soil and, as one of countless human beings, I can’t claim any special place for myself except that, as an Austrian, a Jew, writer, humanist and pacifist, I have always been precisely in those places where the effects of the thrusts were most violent.”
—Stefan Zweig (18811942)
“If I had any doubts at all about the justice of my dislike for Shakespeare, that doubt vanished completely. What a crude, immoral, vulgar, and senseless work Hamlet is. The whole thing is based on pagan vengeance; the only aim is to gather together as many effects as possible; there is no rhyme or reason about it.”
—Leo Tolstoy (1828–1910)