Pre-early polypeptides of bacteriophages T5 and BF23

Nine pre-early polypeptides have been detected after infection with bacteriophage T5 and 10 pre-early polypeptides have been detected after infection with bacteriophage BF23. Only about one-half of the coding capacity of the redundant ends of the phage DNA, which code for pre-early proteins, is needed for these 9 to 10 pre-early polypeptides. The direction of transcription of pre-early genes A1 and A2 has been established from the size of N-terminal polypeptide fragments induced by amber mutants and from the known intragenic loci of the amber mutations. Some pre-early functions appear to be nonessential, because a viable deletion mutant of BF23 fails to induce three and possibly four of the detectable pre-early polypeptides.