 There are no crystal structures available for members of the Dcu family.The two "E. coli" proteins, DcuA (TC# 2.A.13.1.1) and DcuB (TC# 2.A.13.1.2), of the Dcu family are involved in the transport of aspartate, malate, fumarate and succinate, functioning as antiporters with any two of these substrates.They exhibit 36% identity with 63% similarity, and both transport fumarate in exchange for succinate with the same affinity (30 μM).