[Free RNA-binding cytoplasmic proteins are detected in a labile association with polyribosomes]

A special fraction of RNA-binding proteins with a non-specific affinity for RNA is present in the extracts of eukaryotic cells. Earlier these proteins were considered exclusively as a pool of free informosomal proteins. It has been shown that a significant part (about 1/3) of RNA-binding proteins is found in labile association with mono- and polyribosome mass, respectively. The labile-associated proteins dissociate from the complex with mono- and polyribosomes with an increase in the ionic RNA-binding proteins bind to particles due to the non-specific affinity for the exposed part of RNA of mono- and polyribosomes. The decrease of the ionic strength leads to the stabilization of the RNA-binding proteins-polyribosomes complexes and enables purification of these complexes. A direct comparison by the O'Farrell two-dimensional analysis has shown that practically all the proteins that are labile-associated with polyribosomes are present within the preparation of free RNA-binding proteins.