The invention relates to a DNA molecule from maize which codes for a protein with TGase activity and to a gene expression vector comprising said DNA molecule. The invention also relates to the use of the aforementioned DNA molecule or vector in order to produce transformed cells capable of expressing recombinant proteins with TGase activity and to introduce the sequence encoding for a protein with TGase activity into plant cells. In addition, the invention relates to the resulting transgenic plants and cells of microorganisms. Furthermore, the proteins with TGase activity expressed from the above-mentioned DNA sequences can be used, for example, in food manipulation, processing and transformation.