Fine mapping of the inhibitory sequences in the HPV-16 L1 gene. (A) Structures of the indicated expression plasmids. The HPV-16 L1 gene sequences were fused in frame with the EIAV p55gag coding sequence as indicated. Nucleotide 1 refers to the first purine in the translational start codon of the L1 coding sequence. pA, poly(A). (B) Northern blot of total cytoplasmic RNA harvested from HeLa cells transfected with the plasmids shown in panel A. Plasmid pCTAT (42), expressing HIV-1 tat cDNA (33), was included as an internal control for transfection efficiency. L1, HPV-16 L1 gene; EIAV, EIAV p55gag coding sequence.