Identification of Edg1 receptor residues that recognize sphingosine 1-phosphate

Originating from its DNA sequence, a computational model of the Edg1 recept or has been developed that predicts critical interactions with its ligand, sphingosine I-phosphate. The basic amino acids Arg(120) and Arg(292) ion pa ir with the phosphate, whereas the acidic Glu(121) residue ion pairs with t he ammonium moiety of sphingosine l-phosphate. The requirement of these int eractions for specific ligand recognition has been confirmed through examin ation of site-directed mutants by radioligand binding, ligand-induced [S-35 ]GTP gammaS binding, and receptor internalization assays. These ion-pairing interactions explain the ligand specificity of the Edg1 receptor and provi de insight into ligand specificity differences within the Edg receptor fami ly. This computational map of the ligand binding pocket provides informatio n necessary for understanding the molecular pharmacology of this receptor, thus underlining the potential of the computational method in predicting li gand-receptor interactions.