Fz7 complex formation with C-cadherin and PAPC shown by coimmunoprecipitations. For coimmunoprecipitation (co-IP) assays, the indicated constructs were injected into the DMZ of 8-cell–stage embryos. At stage 10.5, DMZ explants were dissected and lysed. In all cases, xFz7 was precipitated with myc antibody (9E10), and complex formation was detected by Western blotting (WB) for the proteins shown (arrows). (A) xPAPC and xC-cadherin coimmunoprecipitations with xFz7. xFz7 interacted with both xC-cadherin and xPAPC. (B and C) xWnt-11–dependent coimmunoprecipitations of xFz7 with xC-cadherin (B) or xPAPC (C). No significant changes could be detected. (D and E) xC-cadherin coimmunoprecipitations with xFz7 in the presence of xPAPC. xPAPC competed with both exogenous (D) and endogenous (E) xC-cadherin for xFz7 complex formation with preference for xPAPC/xFz7 complex. Injection amount was as follows: 1 ng xC-cadherin–EGFP RNA, 1 ng xPAPC-HA RNA, 500 pg xFz7-myc RNA, 40 pg xWnt-11 RNA, and 1 pmol xWnt-11 MO.