FIG. 1.

Nucleotide sequence of the P1 EcoRI-19 restriction fragment. The recognition sequences of the EcoRI restriction endonuclease are underlined at both ends of the nucleotide sequence. Promoter elements and the start codon of the mat gene are in bold. The transition leading to an amber stop codon in P1 vir^s am 132 is indicated by a T above the underlined wild-type CAG codon. Open reading frames are translated into the single-letter amino acid code below the sequence. The genes ref and mat are oriented clockwise, while the res gene is oriented counterclockwise.