Peptide C105Y TFA is a cell-penetrating peptide synthesized based on the amino acid sequence of residues 359-374 of α1-antitrypsin. It enhances the gene expression of DNA nanoparticles.

C105Y, when incubated with human hepatoma cells (HuH7) for as little as 3 minutes, shows nuclear and cytoplasmic fluorescence with a concentration of signals in the nucleus and nucleolus. The peptide quickly targets the nucleolus in an energy-dependent manner, while its membrane translocation and nuclear localization occur without energy. In studying its uptake and trafficking, C105Y is internalized through a pathway that does not involve clathrin or caveolin, though lipid raft-mediated endocytosis might influence its intracellular movement.