Fig. 7. CONT, NRX IV and NRG form a biochemical complex. Co-immunoprecipitation experiments reveal a tripartite complex between CONT, NRX IV and NRG. NP-40 embryonic lysates were immunoprecipitated with anti-NRX IV, anti-CONT, anti-NRG (1B7) antibodies. Controls were performed with anti-CONT pre-immune serum (PI). Immunoblots were probed with anti-NRX IV (A), rat anti-CONT (B) or anti-NRG 3C1 (C) antibodies. Molecular weight standards in kDa are indicated on the left. NRX IV is co-immunoprecipitated with CONT and reciprocally CONT is co-precipitated with anti-NRX IV antibodies. It was not possible to detect CONT in the anti-NRG immunoprecipitate. By contrast, NRG¹⁶⁷ (asterisk) was detected in the immunoprecipitate with anti-CONT antibodies. A doublet of both 167 and 180 kDa NRG isoforms is detected in the NP-40 lysate (arrowheads). (D) COS cells were co-transfected with NRX IV and CONT. NP-40 lysate was immunoprecipitated with anti-NRX IV antibody. CONT is detected in the anti-NRX IV immunoprecipitate.