rpb2

RPB2 refers to the second largest subunit of eukaryotic RNA polymerase II. In the budding yeast Saccharomyces cerevisiae the gene is RPB2, and in animals and other eukaryotes the ortholog is POLR2B. The protein is a core, essential component of RNA polymerase II, forming part of the enzyme's catalytic core together with the largest subunit RPB1. RPB2 contributes to transcription initiation and elongation by supporting the assembly and stability of the polymerase complex and by mediating interactions with transcription factors and the nascent RNA. The carboxy-terminal domain of RPB1 is not part of RPB2, but RPB2 makes contacts with nucleic acids and other Pol II subunits that help position DNA and RNA during transcription.

RPB2 is highly conserved across eukaryotes. It is required for viability; loss or mutation can severely reduce transcription and alter gene expression. The protein is present in the intact Pol II holoenzyme throughout transcription, distinguishing it from some factors that transiently associate with Pol II.

In research contexts, RPB2 is used to study RNA polymerase II structure and function, as well as the mechanics of transcription initiation, elongation, and chromatin interactions. Gene naming conventions vary by species (RPB2 in yeast; POLR2B in humans and other animals).