SNAPC1 is a core subunit of the SNAPc (small nuclear RNA-activating protein complex) that functions as a general transcriptional regulator with dual roles in snRNA and protein-coding gene transcription. As part of SNAPc, SNAPC1 binds to proximal sequence elements (PSE) in snRNA gene promoters and recruits basal transcription factors like TBP and BRF2 to facilitate both RNA polymerase II and III transcription of snRNAs 1. Beyond its canonical snRNA function, SNAPC1 occupancy extends to transcriptionally active protein-coding genes, where it associates with elongating RNA polymerase II and serves as a general transcriptional coactivator required for responsiveness to extracellular signals like EGF and retinoic acid 2. SNAPC1 SUMOylation at lysine residues 245 and 333 is essential for proper snRNA transcription and SNAPc complex assembly, particularly for interaction with SNAPC4 1. Clinically, SNAPC1 has been implicated in suicide risk through rare genetic variants 3 and appears dysregulated in cancer contexts, including renal carcinoma where read-through circular RNAs spanning HIF1α-SNAPC1 promote tumor progression 4, and in acute myeloid leukemia prognosis 5. Additionally, SNAPC1 expression is upregulated during cellular transformation and Onconase-induced stress responses 67.