Fig. 4.

The intramolecular interaction of protein domains in Rspo2. Four-cell stage embryos were injected with RNAs encoding RspoΔF-GFP, RspoΔT-Flag alone or co-injected. The embryos were cultured until stage 12 and lysed for GFP pulldown. (A) RspoΔT-Flag is co-immunoprecipitated (IP) by RspoΔF-GFP. (B) RspoΔT-Flag is co-immunoprecipitated by Rspo2-GFP. (C) Putative mechanistic model of FGF pathway inhibition by Rspo2. The association of Rspo2 with HSPGs prevents FGF ligand binding and signaling.