Nucleotide Sequence of the Hin d‐I‐proximal Part of Simian Virus 40 Hin dII + III Restriction Fragment B. Fifth Part of the T Antigen Gene

The nucleotide sequence of the simian virus 40 DNA segment that lies between the Hin dIII restriction endonuclease cleavage site at map position 0.324 and the Atu I cleavage site at 0.261 has been determined by the base‐specific partial chemical degradation procedure of Maxam and Gilbert. This region comprises 335 base pairs and represents 6.4% of the total SV40 genome and 41% of the restriction fragment Hin d‐B. It connects in the clockwise direction to the restriction fragment Hin d‐I (described in the preceding paper). Hin d‐B is situated in the second half of the early transcription region of the SV40 genome and encodes information (including the termination signal) for the early protein large‐T antigen. In the part of Hin d‐B described here, the DNA strand that has the same polarity as early 19‐S mRNA defines only one open reading frame for translation; the other two are blocked by multiple triplets corresponding to termination codons. The open reading frame is part of one that runs throughout much of the early region: from the second splicing boundary of the large‐T gene (position 0.534) to the information for the large‐T stop signal (position 0.174) near the Hin d‐B/ Hin d‐G junction, and which together with the non‐contiguous DNA segment from position 0.65 (site of the information for the large‐T start signal) to 0.60 (the first splicing boundary) codes for the entire large‐T antigen.