Saccharomyces cerevisiae A49 is a specific subunit associated with RNA polymerase I (Pol I) in eukaryotes. Pol I maintains transcription activities in A49 deletion mutants. However, such mutants are deficient in transcription activity at low temperatures. Deletion analysis of the fusion yeast homolog indicate that only the C-terminal two thirds are required for function. Transcript analysis has demonstrated that A49 is maximising transcription of ribosomal DNA.