They are artificial vectors that have been derived from the naturally occurring Ti plasmid found in bacterial species of the genus Agrobacterium, such as A. tumefaciens.
The T-DNA portion of the binary vector is flanked by left and right border sequences and may include a transgene as well as a plant selectable marker.
Outside of the T-DNA, the binary vector also contains a bacterial selectable marker and an origin of replication (ori) for bacteria.
These genes code for a series of proteins that cut the binary vector at the left and right border sequences, and facilitate transfer and integration of T-DNA to the plant's cells and genomes, respectively.
Another distinguishing feature of pGreen is its large reduction in size (from about 11,7kbp to 4,6kbp) from pBIN19, therefore increasing its transformation efficiency.