Cloning and analysis of the nuclear genes for two mitochondrial ribosomal proteins in yeast

Two mitochondrial ribosomal proteins of yeast (Saccharomyces cerevisiae) were purified and their N-terminal amino acid sequences determined. The sequence data were used for the synthesis of oligonucleotide probes to clone the corresponding genes. Thus, the genes for two proteins, termed YMR-31 and YMR-44, were cloned and their nucleotide sequences determined. From the nucleotide sequence data, the coding region of the gene for protein YMR-31 was found to be composed of 369 nucleotide pairs. Comparison of the amino acid sequence of protein YMR-31 and the one deduced from the nucleotide sequence of its gene suggests that it contains an octapeptide leader sequence. The calculated molecular weight of protein YMR-31 without the leader sequence is 12,792 dalton. The gene for protein YMR-44 was found to contain a 147 bp intron which contains two sequences conserved among yeast introns. The length of the two exons flanking the intron totals 294 nucleotide pairs which can encode a protein with a calculated molecular weight of 11,476 dalton. The gene for protein YMR-31 is located on chromosome VI, while the gene for protein YMR-44 is located on either chromosome XIII or XVI.