Which protein is required for the degradation of extra nucleotides in eukaryotic RNA transcription termination?

The protein required for the degradation of extra nucleotides during eukaryotic RNA transcription termination is Rat1. Rat1 is a 5' to 3' exonuclease that plays a crucial role in the termination process of RNA polymerase II transcription. When RNA polymerase II synthesizes RNA, it may generate additional RNA beyond the polyadenylation site of the transcript. Rat1 binds to the RNA, facilitating the degradation of this excess RNA in a process known as transcription-coupled RNA degradation. This action is vital to ensure that the transcript is properly processed and that the transcription machinery can be effectively recycled for subsequent transcription events.

In contrast, RNA polymerase is primarily responsible for synthesizing RNA, while ribonuclease is a general term for enzymes that degrade RNA but is not specifically involved in termination. Splicosomal proteins are associated with splicing, a separate process from transcription termination. Understanding the specific role of Rat1 highlights its importance in maintaining RNA integrity and proper gene expression regulation in eukaryotic cells.