Has a role in the RNA interference (RNAi) pathway which is important for heterochromatin formation and accurate chromosome segregation. A member of the RNA-induced transcriptional silencing (RITS) complex which is involved in the biosynthesis of dsRNA from primer siRNAs provided by the RNA-directed RNA polymerase (RDRC) complex. Ago1, chp1 and tas3 interact to form the core of the RNA-induced transcriptional silencing (RITS) complex. The RITS complex interacts with the RDRC complex via interaction between ago1 and hrr1. Clr4 has a role in mediating this interaction.