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 phi80-induced RNA at four distinct sites. Nucleotide sequence analysis of the eight cleavage products has shown that the enzyme produces oligonucleotides terminating in 3'-phosphate groups, and that the four 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.