Dynamic modeling of EDG1 receptor structural changes induced by site-directed mutations

EDG1 is a member of the G protein coupled receptor family and serves as a c ellular receptor responsive to phospholipids. EDG1 binds sphingosine-1-phos phate (SPP) with high affinity and lysophophatidic acid (LPA) with low affi nity. A model has been developed, based on an experimentally based model of the structure of rhodopsin, to evaluate the features that contribute to th e different binding affinities of phospholipids for EDG1. The residues pred icted by the model to be important in binding have previously been reported . Twenty mutations expressed transiently in HEK293 cells were evaluated by radioligand binding assays and MAP-kinase assays of receptor activation. Se venteen of these mutations are well explained by the current model. The rem aining three mutations and three additional control mutations have been mod eled using molecular dynamics. Changes in the exposed surface areas of amin o acids in the binding pocket reflect the changes in SPP binding observed f or the modeled mutations. (C) 2000 Elsevier Science B.V. All rights reserve d.