title: Assembly of the mitochondrial membrane system. CBP1, a yeast nuclear gene involved in 5' end processing of cytochrome b pre-mRNA.
abstract: Noncomplementing mutations in a nuclear gene (CBP1) of Saccharomyces cerevisiae D273-10B specifically affect the synthesis of cytochrome b, a mitochondrially encoded carrier of the respiratory chain. The nuclear mutants have been shown to have lowered levels of cytochrome b-specific transcripts. This phenotype is attributed to the inability of the mutant strains to process the 5' end of the cytochrome b pre-mRNA. Impairment of the processing function encoded by the CBP1 gene introduces an instability in the transcripts and promotes nucleolytic degradation. Mutations in CBP1 can be suppressed by a p- genome in which the 5' untranslated leader of the oli1 gene (subunit 9 of the ATPase) is fused near the 5' side of the cytochrome b coding sequence. The rearranged genome allows the cytochrome b gene to be transcribed from the oli1 promoter and results in novel cytochrome b transcripts with the 5' leader sequence of the oli1 mRNA. The presence of the oli1 leader sequence confers stability to the RNA and circumvents the CBP1 processing function.
mesh_terms: D001483:Base Sequence; D003573:Cytochrome b Group / Q000235:genetics*; D005796:Genes; D005800:Genes, Fungal; D005838:Genotype; D007425:Intracellular Membranes / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology*; D009154:Mutation; D009693:Nucleic Acid Hybridization; D009694:Nucleic Acid Precursors / Q000235:genetics*; D012322:RNA Precursors; D012333:RNA, Messenger / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D003573:Cytochrome b Group; D009694:Nucleic Acid Precursors; D012322:RNA Precursors; D012333:RNA, Messenger