Catalysis of the reaction: (E)-4-coumaroyl-CoA + an anthocyanidin 3,5-di-O-beta-D-glucoside = an anthocyanidin 3-O-beta-D-glucoside 5-O-beta-D-[(6-O-(E)-4-coumaroyl)glucoside] + CoA. Caffeoyl-CoA can also act as an acyl donor.
A complex of five proteins, designated NELF-A, -B, -C, -D, and -E in human, that can physically associate with RNP polymerase II to induce transcriptional pausing.