title: Endoribonuclease IV. 2. Further investigation on the specificity.
abstract: The poly(A)-specific endoribonuclease IV produces oligo(A) fragments of a chain length of 10 AMP nucleotides. One enzyme molecule performs 1700 cleavages per min; the cleavages occur randomly. The endoribonuclease IV is a nuclear enzyme which is present in the oviduct of quails in a concentration of 40 000 enzyme molecules per cell. Poly(A) segments on mRNA are selectively hydrolyzed by endoribonuclease IV; the poly(A)-free part of the RNA is not affected. After incubation with the enzyme, a residual oligo(A) stretch of 5 AMP nucleotides remains on poly(A)-rich RNA. The endoribonuclease IV does not disintegrate the polyribosomal complex after incubation in vitro and the enzyme has also no influence on the translational capacity of a cell-free protein-synthesizing system.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D004720:Endonucleases / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008970:Molecular Weight; D009843:Oligoribonucleotides / Q000032:analysis; D010057:Oviducts / Q000201:enzymology; D010944:Plants / Q000201:enzymology; D011061:Poly A; D011132:Polyribosomes / Q000201:enzymology; D011784:Quail; D012260:Ribonucleases / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D009843:Oligoribonucleotides; D011061:Poly A; D004720:Endonucleases; D012260:Ribonucleases