| ironjustice@aol.com 2006-01-09, 11:05 am |
| http://www.answers.com/topic/ferritin
<<snip>>
In the presence of yohimbine, the rate of biosynthesis of ferritin in a
cell-free expression system (rabbit reticulocyte lysate) increased by
40%.
<<snip>>
The up-regulation of ferritin expression using a small-molecule ligand
to the native mRNA.
Tibodeau JD, Fox PM, Ropp PA, Theil EC, Thorp HH
Proc Natl Acad Sci U S A. 2005 Dec 28;
The binding of small molecules to distinctive three-dimensional
structures in mRNA provides a new dimension in RNA control, previously
limited to the targeting of secondary structures with antisense and RNA
interference; such targeting can modulate mRNA function and rates of
protein biosynthesis. Small molecules that selectively bind the
iron-responsive element (IRE), a specific three-dimensional structure
in the noncoding region of the ferritin mRNA model that is recognized
by the iron-regulatory protein repressor, were identified by using
chemical footprinting. The assay used involved an oxoruthenium(IV)
complex that oxidizes guanine bases in RNA sequences. Small molecules
that blocked oxidation of guanines in the internal loop region were
expected to selectively increase the rate of ferritin synthesis,
because the internal loop region of the ferritin IRE is distinctive
from those of other IREs. The natural product yohimbine was found
(based on gel mobility shifts) to block cleavage of the internal loop
RNA site by >50% and seemed to inhibit protein binding. In the presence
of yohimbine, the rate of biosynthesis of ferritin in a cell-free
expression system (rabbit reticulocyte lysate) increased by 40%.
Assignment of the IRE-yohimbine interaction as the origin of this
effect was supported by a similar increase in synthesis of luciferase
protein in a chimera of the IRE and luciferase gene. The identification
of a small, drug-like molecule that recognizes a naturally occurring
three-dimensional mRNA structure and regulates protein biosynthesis
rates raises the possibility that small molecules can regulate protein
biosynthesis by selectively binding to mRNA.
www.raysahelian.com/yohimbe.html
http://www.bodybuildingforyou.com/s...ews/Yohimbe.htm
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