The TGB3 protein of Barley stripe mosaic virus(BSMV) is essential for the virus cell-to-cell movement.Previous study showed that TGB3,together with TGB2,facilitated the location of TGB1 to the plasma membrane.But the interactions between TGB3 and TGB2 or TGB3 are still not thoroughly understood.We investigated the interactions of BSMV TGB3 with itself and with other two TGBps using a Gal4-based yeast two-hybrid system.TGB3 interacted only with itself but not with each of other two TGBps.The self-interaction of TGB3 was also confirmed by pull-down assay.Deletion mutagenesis mapped the self-interacting domain to the C-terminal 37 amino acids (amino acids 87-123),which contain a conserved C-terminal motif.The role of this novel property of BSMV TGB3 in virus cell-to-cell movement was discussed.