Figure 6.—

Relationship between ubiquitination of proteins involved in transcription elongation by RNA polymerase II and by Ty1 transposition. Protein names (in boldface type) required for restricting Ty1 transposition and maintaining target site preference at CAN1 include the Paf complex subunits Cdc73, Paf1, and Rtf1 and the Rad6-Bre1 ubiquitination (+Ub) complex that modifies histone H2B on K123. Rad6-Bre1 may also ubiquitinate additional proteins that have not been identified. The Paf1 complex subunit protein Leo1 is required for restricting Ty1 transposition but is not required for target-site preference at CAN1, and Ctr9 was not analyzed. The Bur1-Bur2 cyclin-dependent protein kinases (+Phos) and the histone H3 methylases (+Me) Dot1 and Set1 were not identified in our screen for Ty1 restriction genes, but may affect Ty1 target preference.