UTP15 is a ribosome biogenesis factor that functions as a core scaffold component of the small subunit (SSU) processome, the earliest precursor complex for eukaryotic 40S ribosomal subunit assembly. UTP15 is required for optimal pre-ribosomal RNA transcription by RNA polymerase I and participates in nucleolar processing of pre-18S rRNA 1. As part of the t-UTP sub-complex within the SSU processome, UTP15 directly interacts with other WD-repeat proteins (CIRH1A and WDR43) and localizes to nucleolar fibrillar centers where it functions as a structural scaffold 2. UTP15 exhibits extremely low mobility in living cells, consistent with its tight association to macro-protein complexes involved in rRNA folding, modification, cleavage, and quality control 34. The protein's phosphorylation regulates its binding interactions during cell cycle progression 2. While UTP15's primary role centers on ribosome biogenesis, it was identified within a chr5 region (5q13) associated with mild branchio-oculo-facial syndrome-like features in a duplication study, though direct pathogenic involvement remains unclear 5. UTP15's essential function in ribosomal RNA processing suggests potential relevance to diseases of impaired protein synthesis, though specific clinical associations require further investigation.