While repression of genes that are not needed provides clear ... the ligand tryptophan is required for the repressor to work (repressible negative regulation). But other operons respond to the ...

Here we describe repressible (PipOFF) as well as inducible (PipON) systems for regulated gene expression in mammalian cells, based on the repressor Pip (pristinamycin-induced protein), which is ...

“RNA can now be the active element that switches off repressible genes in response to the concentration of a cellular metabolite,” writes Tom Cech, from the University of Colorado, Boulder, in an ...