RPB12

RPB12 is a small subunit of RNA polymerase II, the enzyme responsible for transcribing protein-coding genes in eukaryotic cells. It is among the smallest Pol II subunits, with an apparent molecular weight around 12–15 kilodaltons, and it is highly conserved across fungi, plants, and animals. The gene encoding this subunit is designated RPB12 in many species, with orthologs found throughout eukaryotes.

Functionally, RPB12 contributes to the proper assembly and stability of the Pol II core enzyme. In budding yeast, the ortholog Rpb12 is essential for viability, and depletion leads to reduced transcriptional activity, indicating a fundamental role in transcription. It is part of the Pol II complex near the catalytic center and participates in interactions with other subunits, helping maintain the integrity of the transcription machinery during initiation and elongation.

Structural studies show RPB12 as a compact, globular domain that engages in subunit contacts within Pol II. Its small size allows it to act as a structural connector, enabling proper alignment of surrounding subunits and thereby supporting the overall architecture of the polymerase.

In humans and other organisms, RPB12 expression is constitutive and essential for normal transcription; variants are infrequent. There is limited evidence linking RPB12 to specific diseases, but functional defects in RNA polymerase II due to perturbations of its subunits can have broad effects on gene expression and cellular physiology.