JBC, Vol. 254, Issue 19, 9331-9334, Oct, 1979
Mutations in putative intervening sequences of the mitochondrial cytochrome b gene of yeast produce abnormal cytochrome b polypeptides
M. Solioz and G. Schatz
The apoprotein of yeast cytochrome b is translated on mitochondrial
ribosomes and coded for by a split gene which is located in the COB-BOX
region on mitochondrial DNA. With the aid of an antibody against cytochrome
b, we identified the cytochrome b-cross-reacting polypeptides of
respiration-deficient mutants mapping either in coding or intervening
sequences of the cytochrome b gene. Most mutations in the coding regions
caused the accumulation of a single apocytochrome b fragment whose apparent
molecular weight (12,000 to 26,600) depended on the map position of the
mutation. In contrast, mutations in putative intervening sequences often
led to multiple new polypeptides immunologically related to apocytochrome
b. Some of these abnormal polypeptides were considerably larger than wild
type apocytochrome b. This suggests that mutations in intervening sequences
can thus generate aberrant polypeptide products.