Small cytoplasmic RNAs from human placental free mRNPs: Structure and their effect on in vitro protein synthesis

Haya LORBERBOUM*, Martin DIGWEED, Volker A. ERDMANN, Yael SERVADIO, Daniel WEINSTEIN, Nathan DE GROOT, Abraham A. HOCHBERG

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

A new family of small cytoplasmic RNA species (scRNAs) was found to be associated with human termplacental free messenger ribonucleoprotein particles (mRNPs). Placental scRNAs strongly inhibit translation of both homologous and heterologous mRNAs in a cell‐free rabbit reticulocyte system. scRNAs could be resolved into at least four different RNA species. One of the RNA molecules, scRNA species 1, was the most potent protein synthesis inhibitor found among the placental scRNAs. The nucleotide sequence of the scRNA species 1 was determined. In spite of its short length, scRNA species 1 still exhibited a very strong inhibitory effect on the in vitro protein synthesis. scRNAs were found to be complexed with proteins in the form of scRNPs. Proteins of these complexes enhanced the inhibitory effect of scRNAs on in vitro translation. Experiments provided evidence that inhibition of in vitro protein synthesis by the scRNAs is not dependent upon mRNA concentration. However, inhibition can be overcome by increasing the ratio lysate/scRNAs, thus suggesting that scRNAs act on some essential component of the cell‐free system. The degree of inhibition is decreased when scRNAs are added after the start of translation, suggesting that scRNAs (or scRNPs) interfere with the initiation stage of translation, probably acting on an initiation factor(s). Placental scRNAs are unique in their size, being smaller than other known scRNAs. Their association with free cytoplasmic repressed mRNPs in human placenta suggests that scRNAs play a role in the regulation of mRNP metabolism and, consequently, in the control of mRNA translation.

Original languageAmerican English
Pages (from-to)279-287
Number of pages9
JournalEuropean Journal of Biochemistry
Volume155
Issue number2
DOIs
StatePublished - Mar 1986

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