DNA-directed RNA polymerases I, II, and III subunit RPABC1

POLR2E (DNA-directed RNA polymerases I, II, and III subunit RPABC1) is a 210-amino acid subunit of the core RNA polymerase machinery (UniProt: P19388). It is a shared component of RNA polymerases I, II, and III, which collectively synthesize ribosomal RNA precursors, mRNA precursors, and functional non-coding RNAs. Within polymerase II, POLR2E forms part of the lower jaw structure that positions the DNA template within the active site during transcription initiation and elongation.

POLR2E is broadly expressed across tissues as an essential component of the basal transcription apparatus, with no documented disease associations listed in UniProt. The protein participates in fundamental gene expression processes required across all cell types, including neurons.

POLR2E shows evidence of downregulation in Alzheimer's Disease brain tissue. Analysis of post-mortem AD brain compared to age-matched controls using TMT-labeled proteomics across subcellular fractions detected a mean log2 fold-change of −0.30 (Chaparral AD proteomics), indicating reduced POLR2E levels in the disease state. This modest reduction may reflect compromised transcriptional capacity in AD-affected neurons.