This coordination takes place in a “terminal knob” that is visible under electron microscopy which is a large 90S pre-ribosome complex known as ribosomal small subunit processome. This SSU processome contains 12S U3 snoRNP, MPP10 complex, t-UTPs, bUTP, BMS/RCL1 complex, RNA helicases and RNA-binding proteins. The coordination between Pol I transcription and rRNA processing is mediated by t-UTPs which are required for both 18S rRNA processing and Pol I transcription, and in addition, are associated with rDNA. Our previous study identified 1A6/DRIM as the human UTP20 which functions mainly in the processing of 18S rRNA. Proteomics studies have found that yeast UTP20 resides in the 90S preribosome in the nucleolus,. However, whether 1A6/DRIM is a classical UTP or a t-UTP remains unknown. In the present study, we investigated the function of 1A6/DRIM in Pol I transcription and found that 1A6/ DRIM functions as a t-UTP. Further study demonstrated that 1A6/DRIM affected UBF acetylation and raises the possibility that there is a novel mechanism by which t-UTPs activate Pol I transcription via altering modification of UBF or other Pol I transcription preinitiation complex factors. Pol I transcription and rRNA processing are coordinated and stringently controlled in normal cells. This coordination is mediated by the interaction of UBF with pre-rRNA processing factors. The SSU processome has been found to play a role in the coordination of Pol I transcription and pre-rRNA processing. The SSU processome is HhAntag691 assembled on nascent pre-rRNA as a large complex with a multimodular structure. While Pol I transcription is undergoing elongation, the SSU processome participates simultaneously in pre-rRNA processing. Pre-rRNA is sequentially cleaved at A0, A1 and A2. Upon cleavage at the A2 site, the pre-40S particle containing major components of the SSU processome and 18S rRNA departs from the remaining pre-rRNA on which another subset of ribosomal proteins are recruited to form the pre-60S particle. It is known that t-UTPs are required for Pol I transcription and early stages of pre-rRNA processing. Up to now, only seven t-UTPs have been identified in yeast and five t-UTPs have been identified in mammalian cells. However, the mechanisms by which t-UTPs function in Pol I transcription remain unknown. Ribosome biogenesis factors play crucial roles in cell proliferation, and deregulation of these factors, such as Pes1 which functions in 28S rRNA processing, often causes tumorigenesis,. Moreover, 1A6/DRIM has been found to be upregulated in some tumors and we are therefore currently investigating the 1A6/DRIM expression profile in human tumors to determine whether 1A6/DRIM can be used as a diagnostic marker or a therapeutic target in human tumors.