Transglycosidase operating by a ping-pong reaction mechanism. Involved in the synthesis of raffinose, a major soluble carbohydrate in seeds, roots and tubers (By similarity). alpha-D-galactosyl-(1->3)-1D-myo-inositol + sucrose = myo-inositol + raffinose A number of isoforms are produced. According to EST sequences. Expressed in 24 hours imbibed seeds and during leaf senescence. By oxidative stress and by dark treatment. Down-regulated by sucrose, but not by osmotic treatment. Belongs to the glycosyl hydrolases 36 family. Extended N-terminus. Extended N-terminus. Extended N-terminus.