The yeast ADP/ATP carrier. Mutagenesis and second-site revertants.

Results of mutagenesis and selection of spontaneous second-site revertants of the yeast ADP/ATP carrier AAC2 is described. Currently, 50 mutants have been made in AAC2 at 35 locations. Yeast carrying mutations at K38, K48, R96, D149, R152, R204, D249, R252, R253, R254 and R294 are all unable to grow on glycerol. Seven of these mutants have yielded second-site revertants when plated on rich yeast media containing glycerol and ethanol. The R96 mutants and the R254 and R253 mutants produce similar changes in the AAC2 molecule because the same sites are affected by their revertant mutations. This system of mutations and revertants is now poised to yield insights into the dynamics of ADP and ATP transport, and mitochondrial carrier structure in general.