Open AccessLocalisation of an Endonuclease Specific for Double‐Stranded RNA within the Nucleolus and Its Implication in Processing Ribosomal Transcripts
Author(s) -
GRUMMT Ingrid,
HALL Stanton H.,
CROUCH Robert J.
Publication year - 1979
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1979.tb12911.x
Subject(s) - nucleolus , rnase p , rna , ribosomal rna , biology , microbiology and biotechnology , transcription (linguistics) , rna polymerase i , ribosome , biochemistry , rna dependent rna polymerase , gene , cytoplasm , linguistics , philosophy
Nucleoli of both chick embryos and mouse Ehrlich ascites cells contain an enzymatic activity that is very similar to RNase DII, an enzyme isolated from total chick embryos for its ability to degrade double‐stranded RNA. The enzyme can be extracted by low salt/EDTA from nucleoli and is associated with pre‐ribosomal 80‐S and 55‐S particles. Under ionic conditions which are inhibitory for the nucleolytic activity the transcript in vitro of nucleoli is not processed and sediments around 45 S. Under salt conditions which are optimal for the nucleolar enzyme the nucleolar transcripts are cleaved to distinct intermediate‐sized moleculues. Addition of the chicken RNase DII or RNase III to the nucleolar transcription system results in a similar shift of the chain length of the RNA molecules. It is concluded that a nucleolar RNase recognizing double‐stranded regions in the pre‐ribosomal RNA is involved in the maturation of ribosomal RNA.