The sequence context around the AUG initiation codon strongly contributes to the translation initiation step in mammalian and plant cells. Here, we investigated the effect of the three nucleotides immediately upstream of the initiating AUG (positions -3 to -1) on the translation efficiency of a reporter gene, beta-glucuronidase, in dicotyledonous and monocotyledonous plant cells. 2009, The Society for Biotechnology, Japan. All rights reserved.