Topogenesis of heterologously expressed fragments of the human Y4 GPCR

► We have prepared a systematic series of fragments of the human Y4 GPCR. ► The N terminus of the fragments is fused to Lep or Mistic, and the C terminus to either GFP or PhoA. ► GFP fluorescence and PhoA activity are measured to establish the location of the C terminus. ► All fragments assume more than one topology, but often one topology predominates. ► Two pairs of large complementary fragments are produced, purified, characterized by SEC, and shown to interact.