PMID: 6112223May 25, 1981Paper

A ribonuclease-resistant cytoplasmic 10 S ribonucleoprotein of chick embryonic muscle. A potent inhibitor of cell-free protein synthesis.

The Journal of Biological Chemistry
S SarkarC Guha

Abstract

A ribonucleoprotein (RNP) particle sedimenting at 10 S in sucrose gradients had been isolated from the post-polysomal fraction of homogenates of 14-day-old chick embryonic leg and breast muscle by sucrose gradient fractionation and gel filtration. The 10 S RNP contains a 4 S RNA species (base composition: AMP, .3%; GMP, 22.2%; CMP, 24.2%; and UMP, 23.2%), and shows three major bands in the 70-90-nucleotide size range by polyacrylamide gel electrophoresis in 99% formamide. The 4 S RNA does not contain oligo(U)- and oligo(A)-rich tracts. The RNP has a characteristic buoyant density of 1.410 g/ml, which corresponds to an RNA/protein ratio of about 1:4. The UV absorption spectra of the RNP is very distinct from that of its RNA component. Both 4 S RNA and the 10 S RNP are potent inhibitors of translation of a variety of mRNAs such as chick muscle poly(A)+ mRNA, rabbit globin mRNA, EMC virus RNA, and poly(A)- and mRNA of rat liver in micrococcal nuclease-treated rabbit reticulocyte lysate. The inhibitory action of the RNA and the RNP on mRNA translation appears to involve the initiation process. The RNA and RNP do not have a nuclease activity associated with them. The hyperchromicity profile of the inhibitory RNA with increasing temp...Continue Reading

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