The Chp1-Tas3 core is a multifunctional platform critical for gene silencing by RITS

The RITS complex links the RNAi pathway with centromeric heterochromatin formation in fission yeast and comprises the chromodomain protein Chp1, the GW protein Tas3 and the argonaute protein Ago1. X-ray analysis of the structured core of the Chp1–Tas3 subcomplex reveals the presence of a C-terminal PIN domain in Chp1, which contributes to post-transcriptional gene silencing of subtelomeric transcripts independently of RNAi.