Use of a peptide vector for intracellular addressing of a substance of interest, said vector essentially comprising a peptide which is derived from maurocalcine corresponding to the following sequence (I): Z-X.sub.1-X.sub.2-X.sub.3-X.sub.4-X.sub.5-X.sub.6-X.sub.7-X.sub.8-X.sub.9- -X.sub.10-X.sub.11-X.sub.12-X.sub.13-X.sub.14-X.sub.15-X.sub.16-X.sub.17-X- .sub.18-X.sub.19-X.sub.20-X.sub.21-X.sub.22-X.sub.23-X.sub.24-X.sub.25-X.s- ub.26-Z', wherein X.sub.1 and X.sub.26 each represent a cysteine, X.sub.2 to X.sub.25 each represent an amino acid or are absent, X.sub.7, X.sub.10, X.sub.11, X.sub.12, X.sub.13, X.sub.14, X.sub.15, and X.sub.16 are always present, and X.sub.10, X.sub.11, X.sub.13 and X.sub.14 each represent a lysin or an arginine, and Z and/or Z' are absent or each represent a sequence of 1-35 amino acids, with the exception of the peptide having SEQ ID NO: 1 in the list of sequences contained in the annex.