Figure 3.

Comparison of Lhx3-bound Ldb1_LID and Isl1_LBD. Interaction maps of (A) Lhx3_LIM1+2 and Ldb1_LID and (B) Lhx3_LIM1+2 and Isl1_LBD. Residues from Ldb1_LID are shown as yellow boxes and those from Isl1_LBD as green boxes. Residues from Lhx3 that form contacts with the LIDs are classed as indicated. (C, D) Structural alignment over the backbone atoms of (C) Lhx3_LIM1 and (D) Lhx3_LIM2 showing the side-chain heavy atoms of Isl1_LBD (green) and Ldb1_LID (orange). The Lhx3 LIM domains from the Isl1_LBD structure are shown as a grey surface. (E) Structure-based sequence alignment of Isl1_LBD and Ldb1_LID. Asterisks show residues that occupy equivalent positions in the structures. Key Lhx3-binding residues in (F) Ldb1_LID and (G) Isl1_LBD. Lhx3_LIM1+2 in each case is shown as a surface model (grey) with Ldb1_LID (yellow) or Isl1_LBD (green). For Ldb1_LID, the side chains of key residues from alanine scanning mutagenesis screens are classed as having a strong (red), moderate (orange) or weak (yellow) effect, whereas for Isl1_LBD the indicated residues (green) all have a strong effect.