Fusion proteins that contain the fusion of (i) a peptide of less than 100 amino acids comprising a first amino acid sequence comprising AASSG (SEQ ID NO: 1) and a second amino acid sequence comprising XAGXDXXTEXPXS (SEQ ID NO: 2), wherein X designates any amino acid, and (ii) a protein transduction domain (PTD) are provided, along with pharmaceutical compositions containing the fusion protein. The proteins can be used to treat Huntington's disease.