Figure 3: Comparison of various important regions of XPA from human and hydra. (a) Zinc-finger motif: seven amino acids (marked by filled circle) of the zinc finger including the CX2C motif near C-terminal are conserved between the two species, while two (marked by open circle) are conservative substitutions. (b) RPA70 binding region: seventeen out of 24 residues are conserved between human and hydra XPA while 5 more are similar. (c) Three out of 4 residues of G motif of ERCC1 binding region are conserved between human and hydra XPA, while the E motif is fairly variable.