Characterization of VPC03090-P as a ligand for the different subtypes of the S1P receptor.

VPC03090-P binding parameters for recombinant mS1P1 and hS1P1–5 receptors. Activity of VPC03090-P at the S1P receptor was determined from a GTP[γ-35S] binding assay carried out using membranes prepared from CHO cells expressing each of the S1P receptor subtypes separately (except S1P2). Elevated levels of bound GTP[γ-35S] in response to increasing VPC03090-P concentrations were designated as agonist activity, whereas a rightward shift in the concentration-response curve of S1P upon coapplication of VPC03090-P at a fixed concentration was designated as antagonist activity. EC50 values were determined by nonlinear regression analysis from a sigmoidal dose-response curve fit of VPC03090-P concentration-response data. In the case of antagonism, Ki values were obtained by Schild Regression analysis of GTP[γ-35S] assay data as described under Materials and Methods. Affinity values (Ki or Kd) were independently determined from the Cheng-Prusoff calculation using IC50 values obtained in a radioligand binding assay as detailed under Materials and Method. S1P2 receptor activity in response to VPC03090-P was evaluated using a Ca2+ mobilization assay.

S1P ReceptorVPC03090-P ActivityEC50Emax Relative to S1PKi from Schild RegressionKi from Radioligand BindingKd from Radioligand Binding
hS1P2No activityN.A.N.A.N.A.N.A.N.A.
hS1P5Partial agonist2.40.26N.A.N.A.2.3
  • N.A., not applicable.