CBP7 codes for a co-factor required in conjunction with a mitochondrial maturase for splicing of its cognate intervening sequence.

Maturases are required for the processing of their cognate intervening sequences in the mitochondrial cytochrome beta pre-mRNA. In this paper we characterize a nuclear gene, CBP7, already known to be required for the translation of the cytochrome b transcript; we present further evidence that it is also required as a co-factor in conjunction with the maturases for the efficient processing of their intervening sequences. Results are based on Northern blot analyses which show that in cbp7 mutants with the short cytochrome b gene the maturase encoding intervening sequence fails to be excised although, at the same time, at least wild-type levels of the maturase are present as indicated by antibodies specific to it in Western blot analyses.