Identification of the SV40 agnogene product: a DNA binding protein

The proximal late region of the SV40 genome (map positions 0.72-0.76) contains an open nucleotide reading frame^1,2 called the agnogene³ because its product had so far not been detected. We report here the detection of a novel protein of molecular weight (M_r) 7,900 (61 amino acids) in cells lytically infected by SV40; its identity has been confirmed by comparing the amino-terminal sequence with that predicted from the SV40 nucleotide sequence. This so-called agnoprotein accumulates late in the lytic cycle and has a relatively short half life of ~2 h. The highly basic nature of the protein and its affinity for both single-stranded and double-stranded DNA suggests that it may have a regulatory role in nucleic acid-protein interactions.