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