N-Cerulean corresponds to an N-terminal portion (amino acid residues 1-173) of the Cerulean fluorescent protein (FBrf0213066). If the N-Cerulean split fluorescent fragment is brought together with a complementary split fluorescent fragment in vivo, a functional fluorescent protein may be reconstituted. N-Cerulean is designed for use in the bimolecular fluorescence complementation (BiFC) technique, in which a pair of complementary split fluorescent fragments is fused to interacting peptides to study protein-protein interactions in vivo (PMID:11983170).