Effect of RalBP1 on the constitutive mGluR1a internalization. a, A schematic representation of various RalBP1 truncation/deletion mutants. b, Time course for constitutive FLAG-mGluR1a internalization in the absence (control) and presence of wild-type RalBP1 or RalBP1 truncation/deletion mutants. HEK 293 cells were transiently transfected with 7 μg of FLAG-mGluR1a and 7 μg of empty vector or myc epitope-tagged RalBP1, μ2BD, μ2BDΔ, or RalBDΔ pcDNA3.1 plasmid cDNAs. The data represent the mean ± SE of five independent experiments. c, Representative immunoblot demonstrating the lack of coimmunoprecipitation of RalBP1 with FLAG-mGluR1a in 500 μg of total protein from cell lysates. Lysates were immunoprecipitated using a monoclonal anti-FLAG antibody. myc-RalBP1 expression is shown in the corresponding cell lysates (100 μg of total protein). The data shown are representative of four independent experiments. BD, Binding domain.