[ PDB file ] [ PubMed link ]
In developing neuronal tissue expression of the key specification factor Lhx3 is supplemented by the redundant protein Lhx4. In motor neurons the balance between Lhx3 and Isl1 is critical for proper cell fate determination. In order to achieve the correct stoichiometric balance between Lhx3/4 and Isl1, Isl2 is additionally expressed to supplement Isl1 protein levels. The structure of the Lhx4 LIM domains complexed with the Isl2 LIM-interaction domain illustrates strong structural conservation in the interactions made between Lhx3/4 and Isl1/2 (when compared with our Lhx3/Isl1 structure). This emphasises the need to so strictly preserve these redundant interactions for the correct developmental outcome.