E. Peter Geiduschek and Michael S. Bartlett are in the Department of Biology and Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0634, USA.
A backbone model of ten subunits of yeast RNA polymerase II has been derived from the ongoing analysis of its crystal structure. Notable features include 'jaws' for holding DNA, a putatively RNA-regulated 'sliding clamp', two 'pores' located in the vicinity of the catalytic center, and a high degree of similarity with the structure of a bacterial RNA polymerase.
