A potato proteinase inhibitor II gene (pin2T) was isolated and characterized both at molecular and functional levels. The open reading frame as well as the 5′ and 3′ flanking regions were sequenced. The 5′ flanking region of the pin2T is highly homologous (91% identity) with that of pin2K from -767 to +29 relative to the transcription start site of the wound-inducible pin2K. The 5′ flanking region was linked to the reporter genes (chloramphenicol acetyl transferase, CAT; or β-glucuronidase, GUS) coding sequences in constructions that contained the terminator from the wound-inducible pin2K gene. The chimeric genes were transferred to tobacco plants using Asrobacterium tumefaciens. The presence of the constructions in the transgenic plants was confirmed by polymerase chain reaction (PCR). Expression of CAT or GUS activities in transgenic tobacco plants driven by pin2T promoter indicated that pin2T is not a wound-inducible gene. Comparison of pin2T promoter sequence with that of the wound-inducible pin2K indicates that there are four small deletion which are located at -221 to 200, -263 to -254, -523 to -462, and -759 to 708 relative to the transcription start site of pin2K. When these deleted sequences are searched through Genebank, we identified one sequence that is found three times in pin2K and is completely deleted from pin2T. This sequence, 5′-AGTAAA-3′, is found in a wide variety of other wound-inducible genes but is not frequently found in the published promoter sequences of the other plant genes. A third deletion located at -523 to -462 relative to the transcription initiation site of pin2K, was moderately homologous (72% identity) with a putative sucross-responsive element of sucrose-inducible genes. Deletion of this sequence was correlated with a loss of sucross inducibility in the pin2K promoter.