This is the nonaarginine form of the cell-permeable BID BH3 peptide. The supplied sequence begins with nine consecutive arginine residues followed by the BID BH3 segment, and the molecular weight exceeds the octaarginine version (LT1052) by approximately 156, the mass of one arginine residue. Nonaarginine is among the most frequently used cationic cell-penetrating tags. Uptake of polyarginine peptides scales with guanidinium content up to a point, which is why R8 and R9 tend to be the lengths chosen in practice, and studies of polyarginine delivery with attached cargoes have examined how the cargo itself shifts that optimum. Because the difference between this product and LT1052 is a single residue on an otherwise identical construct, the pair is useful for testing delivery efficiency directly in a given cell type rather than assuming a published optimum transfers. The cargo is the BID BH3 domain, which acts as a direct activator of the apoptotic effectors BAK and BAX rather than merely occupying anti-apoptotic proteins, so cytosolic delivery is expected to produce a functional apoptotic response. As with any highly cationic peptide, include a carrier-only control at matched concentration to separate cargo-driven death from membrane effects of the polyarginine tag, and prefer functional readouts over uptake imaging alone, since material trapped in endosomes is counted by the latter but cannot act. | 