Protected nucleotide sequences in nuclear ribonucleoprotein

Abstract

The rapidly labeled nuclear RNA in human carcinoma cells which is protected by protein from digestion by staphylococcal nuclease (EC 3.1.4.7) was investigated. A simple and discrete sequence specificity was not found, but the protected RNA fragments are rich in G + C and were shown by fingerprinting to comprise a nonrandom subset of all heterogeneous nuclear RNA (hnRNA) sequences enriched in the sequences AGC, GGC, AGGC and GAGC. There was no detectable enrichment for double-stranded RNA in the protected fraction. This is the 1st evidence that the association of any protein with hnRNA is nonrandom with respect to nucleotide sequence.