RSC, a for growth essential chromatin-remodeling complex of Saccharomyces cerevisiae, is composed of 15 subunits. Rsc1p and Rsc2p are highly homologous proteins and are contained in distinct RSC complexes. We found that both rsc1Δ and rsc2Δ homozygous diploids showed reduced sporulation with decreased expression of IME2 and that rsc1Δ, but not rsc2Δ, produced aberrant asci containing one to three spores. Overexpression of RSC2 in rsc1Δ recovered the sporulation efficiency but not the production of aberrant asci. In contrast, overexpression of RSC1 in rsc2Δ did not alleviate its sporulation defect. These results suggest that both Rsc1p and Rsc2p share overlapping functions on IME2 expression, with a prominent role for Rsc2p, whereas Rsc1p has an additional function in the late steps of the sporulation process. [ABSTRACT FROM AUTHOR]