C-YFP corresponds to the C-terminal portion of the YFP fluorescent protein. If the C-YFP split fluorescent fragment is brought together with a complementary split fluorescent fragment in vivo, a functional fluorescent protein may be reconstituted. C-YFP is designed for use in the bimolecular fluorescence complementation (BiFC) technique, which is used to study protein-protein interactions in vivo (PMID:11983170).