The present invention relates to a transport protein which can be obtained by modifying the heavy chain of the neurotoxin formed by Clostridium botulinum wherein (i) the protein binds specifically to nerve cells with a higher or lower affinity as the native neurotoxin; (ii) the protein has an increased or reduced neurotoxicity compared to the native neurotoxin, the neurotoxicity being preferably determined in the hemidiaphragma assay; and/or (iii) the protein comprises a lower affinity against neutralizing antibodies compared to the native neurotoxin. The invention also relates to methods for producing the same and the use thereof in cosmetic and pharmaceutical compositions.