SEQUENCE OF THE GENE FOR ISO-1-CYTOCHROME-C IN SACCHAROMYCES CEREVISIAE

The complete sequence of the iso-1-cytochrome c gene of yeast has been determined. The coding region of the gene contains no intervening sequences. The coding strand of the DNA immediately upstream from the coding region contains many fewer G residues than the rest of the coding strand both within and beyond the carboxy terminus of the coding region. One consequence of the reduced number of G residues in this region is the absence of the sequence ATG for 122 nucleotides upstream from the initiating ATG. Together with previous studies on the mRNA and the genetics of yeast iso-1-Cytochrome c, the sequence supports a model in which translation starts at the first AUG down-stream from the 5′ terminus of the mRNA, with no other sequence requirements. It also is evident that iso-1-cytochrome c is synthesized directly and not through an intermediary, longer precursor protein, as is often the case for proteins that interact with membranes. The DNA upstream and downstream from the coding region contains sequences which are potential transcription start and stop signals. The sequence confirms the assignments of non-sense and missense mutations throughout the coding region of the gene and provides a rationale for some mutational characteristics of the gene. Part of the sequence was determined using two new strategies for the Sanger terminator method, both of which obviate the need for restriction fragment isolation and template strand separation. © 1979.