The primary structure of rabbit β-globin mRNA as determined from cloned DNA

Abstract

The rabbit β-globin DNA insertion of the hybrid plasmid PβG1 (Maniatis et al., 1976) was sequenced by the method of Maxam and Gilbert (1977). A sequence of 576 nucleotides was determined and verified by pyrimidine tract analysis of double-stranded DNA, synthesized in vitro starting from β-globin mRNA. The derived sequence is in complete agreement with previously reported partial mRNA sequencing data and with the predictions from the primary structure of the protein. Moreover, the globin DNA insertion is missing only 13 nucleotides corresponding to the 5′ terminal sequence of the mRNA. The rabbit β-globin mRNA consists of a coding region of 438 nucleotides, flanked by a 5′ noncoding region of 56 nucleotides (including the initiation codon AUG but not the 7-methyl-guanine of the “cap structure”) and by a 3′ non-coding region of 95 nucleotides (including a UGA termination codon). The features of the mRNA sequence are discussed with specific attention to the selective use of particular codons, the probable existence of extensively base-paired segments at the 5′ terminal region and the ribosome binding site. The faithful representation of β-globin mRNA in the PβG1 DNa insertion establishes the validity of using cloned DNA, initially derived from double-stranded DNA transcripts of mRNA, for studying the structure of eucaryotic genes.