Ty3 is a retrotransposon of S. cerevisiae. The Ty3 genome contains two open reading frames termed, GAG3 and POL3 that encode homologs of retroviral proteins. Cellular proteins are postulated to act at several points in the Ty3 lifecycle. The assembly and maturation of Ty3 VLPs are thought to involve chaperone proteins and the late step of integration requires components of the RNA pol III transcription complex TFIIIB and TFIIIC to mediate this event. A genetic screen to isolate cellular genes that when expressed at high levels suppress Ty3 transposition was performed. The goal was to identify proteins that would directly negatively regulate Ty3 as well as those that would form nonfunctional or mislocalized complexes. Two classes of genes were isolated, one comprised primarily of translation components that reduced transposition by 2-3 fold. The second group reduced transposition by 7 fold. Two novel genes named STT1 and STT2 for suppressors of Ty3 transposition were in the second group. STT1 contains a putative RING-finger domain . Neither gene has highly similar homologs in the yeast protein database. Neither STT1 or STT2 markedly alters Ty3 proteins or levels of Ty3 DNA when expressed at high levels, indicating they may act late in the lifecycle. Characterization of these genes to determine their cellular function and the point at which they act to reduce transposition is ongoing.