the pattern of synthesis of the enzymes in leu-5ts revertants , the reciprocal relationship of the production of the two enzymes in response to a negative regulatory element , presumably of mitochondrial origin , as well as the lack of detectable structural homology , led to the proposal that the phenotype of leu-5ts results from a mutational alteration in the structural gene for the cytoplasmic enzyme in a region involved in the initiation of transcription of the adjacent gene for the mitochondrial enzyme .
C0010834
cytoplasmic
C0026237
mitochondrial