The results in the present study emphasize that in Arabidopsis thaliana genome, gamma-GTase encoded by a gene family comprised of four genes. Three of these genes are functionally expressed while the fourth is a pseudogene. The three functional genes express different active protein isoforms that appeared to have different functions. Two genes (GGT1 and GGT2) are structurally similar and expresses proteins with the same molecular weight and both target to the same cellular compartment (plasma membrane). However, both demonstrated different tissue localization, physiological activities and different patterns of response to environmental stress. The majority of GGTI encoded by the first gene was localized in the rosette leaves, It is also expressed throughout the whole plant.