Characterization of ribonuclease NU cleavage sites in a bacteriophage phi80 induced ribonucleic acid

Ribonuclease NU, an endoribonuclease isolated from human KB tissue culture cells, can cleave a bacteriophage phi 80 induced RNA at 4 distinct sites. Nucleotide sequence analysis of the 8 cleavage products has shown that the enzyme produces oligonucleotides terminating in 3' phosphate groups, and that the 4 cleavage sites are in the only nonhydrogen bonded region of the substrate. Various aspects of the cleavage reaction with this RNA and with other substrates are discussed.