perturbagens peptides true This approach is based on the expression of peptides that bind to specific target proteins thereby interfering with their activity. In a standard approach the interfering peptide is expressed by genetic fusion to a stable protein scaffold. Interfering peptides can also be introduced into cells by fusing them to proteins or peptides (homeodomains, Tat protein.) having the property of penetrating the cell membrane. The peptide-carrier fusion protein is either synthesized chemically or produced in vivo, normally in bacteria. When the purified fusion protein is added to a cell culture, it penetrates the cell membrane thereby permitting the fused peptide to interfere with its target protein. OBSOLETE as such method can be described using the biological role inhibitor (MI:0586). perturbagens pep PSI-MI MI:0259