The rate of import and assembly of F1-ATPase in Saccharomyces cerevisiae.

Subunit specific antiserum can be employed to study the course of ATPase assembly in mitochondria isolated from bakers' yeast. Comparing rates of subunit import with rates of enzyme assembly indicated that no substantial pool of unassembled subunits exists for the three largest ATPase peptides (alpha, beta, and gamma). Blocking import of specific ATPase subunits, however, did reveal a possible accumulation of unassembled alpha and gamma subunits in isolated mitochondria. The kinetic experiments also revealed a lag in the import of beta subunit relative to the uptake of alpha and gamma precursors. Experiments conducted in yeast cells confirmed that beta subunit is assembled soon after it is imported, but did not indicate a delay in import relative to the other subunits of F1.