0000000000187435
AUTHOR
Rudolf Messer
Differential polyadenylation pattern of ovalbumin precursor RNAs during development.
The expression of the ovalbumin gene encoding for the major hen oviduct protein slows down with age. Analysis of Northern blots of electrophoretically separated total and poly(A) + RNA from oviducts of hens of different age with an ovalbumin-specific probe (nick-translated 9.5 kb ovalbumin gene DNA cloned into pBR322) revealed that the largest high molecular weight ovalbumin RNA precursor (7.9 kb band, representing the putative primary transcript of the ovalbumin gene) was most intense if total RNA from non-egg-laying old hen oviduct was checked as compared to that from egg-laying mature animals. On the other side, the 7.9 kb RNA precursor band was readily detected in the poly(A) + RNA from…
BASE-SPECIFIC RIBONUCLEASES POTENTIALLY INVOLVED IN HETEROGENEOUS NUCLEAR-RNA PROCESSING AND POLY(A) METABOLISM
Abstract Polyadenylation and splicing of heterogeneous nuclear RNA, two crucial steps in mRNA processing, are apparently enzymically mediated processes. This contribution summarizes the properties and the presumed functions of the known poly(A) catabolic enzymes (endoribonuclease IV and V, 2′,3′-exoribonuclease) as well as those of the pyrimidine-specific endoribonucleases associated with snRNP—hnRNP complexes (endoribonuclease VII, acidic p I 4.1 endoribonuclease and poly(U)-specific U1 snRNP-nuclease).
Association of a polyuridylate-specific endoribonuclease with small nuclear ribonucleo-proteins which had been isolated by affinity chromatography using antibodies from a patient with systemic lupus erythematosus.
Immunoglobulins, containing antibodies against U1-snRNP, have been prepared from a patient with systemic lupus erythematosus. After coupling these antibodies to a Sepharose matrix, U-snRNPs have been isolated and purified from rat liver nuclei by use of immunoaffinity chromatography. The resulting RNPs had the typical protein pattern of U-sn RNPs and a sedimentation coefficient of 12 S. The U-snRNP preparation was associated with an endoribonuclease which required Mg2+ for optimal activity. The enzyme, with an pH optimum of 6.2, degraded only poly(U). Other single-stranded polyribo- and polydeoxyribonucleotides, tRNA, as well as double-stranded RNA and DNA were not digested. The products of…