The goal of this collaboration is to elucidate mechanism of RNA synthesis by eukaryotic multi-subunit RNA polymerase II (Pol II). The project involves a site-directed mutagenesis of the catalytic Rpb1 and Rpb2 subunits of Pol II, purification of the mutant enzymes from the yeast cells and their biochemical characterization. A score of mutants with altered elongation properties, such as transcription pausing and arrest, has been characterized.