Two regions of the adenovirus 2 genome specify families of late polysomal RNAs containing common sequences.

Abstract

Late cytoplasmic [human oral carcinoma KB cells] RNA specified by 2 regions of the adenovirus 2 genome (39.3-51.8 and 70.7-83.4 map units) were analyzed by size fractionation of poly(A)-[3H]RNA and subsequent hybridization to DNA fragments. Both regions encode RNA whose sequence content exceeds the coding capacity of the region. These multiple transcripts are likely to function as mRNA, because they are present on polyribosomes. The DNA segment 39.3-51.8 specifies 27S, 22S and 18S RNA. The genome sites specifying these 3 size classes were determined by hybridizations with 7 different DNA fragments from this region of the genome. The 3'' termini of all 3 size classes are specified by sequences near a common site, position 50.1. The 27S RNA includes sequences beginning near 39.3, the 22S RNA contains sequences from 41.0, and the 18S RNA includes sequences from approximately 45.3 on the unit genome. A 2nd family of four RNA is transcribed from 70.7-83.4. These 28S, 22S, 18S and 16S RNA have a relationship similar to the RNA transcribed from 39.3-51.8. Sequences near the 5'' ends of these 4 size classes are specified by different genome sites. The 3'' termini of all 4 size classes were localized near map position 80.4. The synthesis of families of RNA may allow the translation of multiple polypeptides from a genome segment that has only 1 terminator site for mRNA synthesis.