A homology model of ISL1 based on the three-dimensional structural model of human rhombotin-2 (PDB entry 2xjy), with the fragment of the LID protein from PDB entry 2xjy retained. (a) A surface representation of the interacting proteins. The ISL1 protein model is shown in white, while the LID protein is in red. (b) Secondary structure representation of the two proteins. The two LIM domains of the ISL1 protein are colored yellow and orange, with the remainder of the protein shown in purple. The LID fragment is shown in red. The crucial interaction between Tyr71 of ISL1 and Asp354 of the LID is shown by the stick representation of the two interacting side chains (indicated by the blue arrow). The green spheres correspond to the zinc atoms bound by the zinc fingers of the LIM domains. The images were generated using PyMol .