Isolation from Friend erythroleukemia cells of an RNase‐sensitive nuclear matrix fibril fraction containing hnRNA and snRNA

Publisher Website
Google Scholar
Abstract
Chromatin-depleted nuclei (CDN) were prepared from Friend erythroleukemia cell nuclei by partial digestion with DNase I and extraction of the chromatin by 2 mM EDTA as described in a previous paper (Long and Ochs, 1983). These structures contained dense networks of matrix fibrils surrounded by distinct laminae but no morphologically distinct residual nucleoli. CDN disrupted by gentle shearing or 1 .mu.g/ml RNase were fractionated into laminae and matrix fibrils by differential centrifugation. Protein composition of the lamina fraction was dominated by 2 prominent lamina proteins that were not detectable in the matrix fraction. Mild RNase treatment led to a conversion of the fibrous network to a particulate morphology while mild shearing resulted in an apparently unaltered fibril fraction. The matrix fibril fractions contained hnRNP [heterogeneous ribonucleoprotein] proteins and sn[small nuclear]RNA. EDTA-prepared CDN may provide a system for studying snRNP-hnRNP interactions and hnRNP processing that is less complex than intact nuclei.