The crystal structure of the Homer EVH1 domain . (a) Ribbon diagrams of the Homer1 EVH1 domain, with five residues of mGluR1 (residues 1,146-1,150) as a representative bound ligand in red. The side chains of the adjacent serine and proline in the bound ligand are oriented away from the Homer surface, and the phenylalanine residue forms a unique contact that is not shared by other EVH1 domains (not shown). (b) A surface representation of the Homer EVH1 domain, showing the location of residues that are essential (red) and nonessential (light blue) for binding to ligand (dark blue). Reproduced with permission from .