Isolation and structure of a rat cytochrome c gene.
We screened a Charon 4A-rat genomic library using the cloned iso-1 cytochrome c gene from Saccharomyces cerevisiae as a specific hybridization probe. Eight different recombinant phages homologous to a coding region subfragment of the yeast gene were isolated. Nucleotide sequence analysis of a 0.96-kilobase portion of one of these established the existence of a gene coding for a cytochrome c identical in amino acid sequence with that of mouse. The rat polypeptide chain sequence had not previously been determined. In contrast to the yeast iso-1 and iso-2 cytochrome c genes, neither of which have introns, the rat gene contains a single 105-base pair intervening sequence interrupting glycine codon 56. The overall nucleotide sequence homology between cytochrome c genes of yeast and rat is about 62%, with areas of greater homology coinciding with four regions of functionally constrained amino acid sequences. Two of these regions displayed 85-90% DNA sequence homology, including the longest consecutive homologous stretch of 14 nucleotides, corresponding to amino acids 47-52 of the rat protein. Somewhat less homology was observed in the DNA-specifying amino acids 70-80, which are invariant residues in most known cytochrome c molecules. Thermal dissociation of the yeast probe from the homologous rat DNA was at about 58 degrees C in 0.39 M Na+. These results establish that cytochrome c genes may be isolated by interspecies hybridization between widely divergent organisms.
D000595:Amino Acid Sequence; D000818:Animals; D001435:Bacteriophages / Q000235:genetics; D001483:Base Sequence; D003574:Cytochrome c Group / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant / Q000302:isolation & purification*; D004926:Escherichia coli / Q000235:genetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D051381:Rats / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013045:Species Specificity
D003574:Cytochrome c Group; D004274:DNA, Recombinant; D004262:DNA Restriction Enzymes