In a previous study we demonstrated that a homeobox peptide corresponding to the 60 amino acid long DNA-binding region of the Drosophila antennapedia homeoprotein was capable of crossing the plasma membrane of cells in culture. This finding has led us to investigate whether chimeric molecules encompassing the homeobox would behave in a similar manner. We demonstrate here that a peptide of 93 amino acids composed of the homeobox and of the C terminus of Rab3, a small GTP-binding protein, crosses the membrane of myoblasts, myotubes and neurons and is conveyed to their nuclei.

This transport is highly efficient, is observed in all the cells present in the culture and occurs at 37°C and 12°C without quantitative peptide degradation. Beyond its theoretical implications for our current views on cellular interactions, this finding could have technical repercussions on the development of drugs with intracellular targets.