Isolation of rapidly labeled RNA from mouse L-cells using cupric sulfate

Cultured mouse L-cells, pulse labeled for 5 min with 3H-uridine, were gently suspended in 0.5mM cupric sulfate and 0.5% sodium dodecyl sulfate at 4 degrees C and treated with cold phenol. Only the RNA, containing less than 1% DNA, was extracted by this procedure. The rapidly labeled ribosomal RNA precursors (44S, 34S) and cytoplasmic 8S RNA showed specific activities higher than that of tRNA and were present in the RNA fraction insoluble in 2M NaCl.