The present invention relates to a plant vacuole targeting sequence X.sub.1X.sub.2X.sub.3PX.sub.4 wherein X.sub.1 is a hydrophobic amino acid, X.sub.2 is a basic amino acid, X.sub.3 is a hydrophobic amino acid, P is proline; and X.sub.4 is a hydrophilic amino acid, such as the sequences IRLPS, IKLPS, LRLPS and LKLPS. The vacuole targeting sequence may be present in a chimeric protein linked to an amino acid sequence of a heterologous protein to facilitate vacuole vacuole targeting of the expressed chimeric protein in a plant cell. The invention is applicable to production of expressed, chimeric proteins in monocots and dicots, and in particular monocots such as cereals and sugarcane.