A study of ribonucleoproteins: The sequence of rabbit 18S ribosomal RNA and the identification of proteins associated with messenger RNA

This study considers the functional role of ribosomal RNA and messenger ribonucleoproteins in the translational regulation of gene expression. The primary structure of rabbit 18S ribosomal RNA was determined by nucleotide sequence analysis of the RNA directly. Rabbit 18S RNA was cleaved with either T1 ribonuclease or RNase H, using a Pst 1 DNA linker to generate a unique set of overlapping fragments spanning the entire molecule. Both intact and fragmented 18S RNA were end-labeled with 32P and base-specifically cleaved enzymatically and chemically. Nucleotide sequences were determined from long polyacrylamide sequencing gels run in formamide. To assess functional roles of RNA in gene expression, specific mRNA-protein interactions were also examined. Eukaryotic mRNA is associated with specific proteins that may be important in translational regulation and mRNA stability; mRNP complexes were reconstituted in a message-dependent, cell-free rabbit reticulocyte translation system, using unique mRNA species transcribed in vitro with SP6 polymerase. Transcripts of both rabbit and human β-globin cDNA were labeled with 32P either throughout the molecule ore selectively at the 5' and 3' terminus