The variable locations of the nut sites indicate that this event is linked neither to initiation nor to termination, but can occur to RNA polymerase as it elongates the RNA chain past the nut site. Phages that are related to lambda have different N genes and different antitermination specificities. The region on the phage genome in which the nut sites lie has a different sequence in each of these phages, and each phage must therefore have characteristic nut sites recognized specifically by its own pN.