Have Your PIC!

摘要

RNA polymerase Ⅱ (Pol Ⅱ), the enzyme that transcribes protein-coding genes, requires additional factors to accurately initiate transcription from promoter-directed start sites. These general transcription factors (GTFs) assemble with Pol Ⅱ into a pre-initiation complex (PIC) that is a key intermediate in the transcription activation pathway (1). The main role of the GTFs is to accurately position and orient Pol Ⅱ on the DNA template and to facilitate access of the catalytic site to the transcribed strand. Recent structural studies, including the cryoelectron microscopy (cryo-EM) reconstruction of the yeast PIC by Murakami et al. on page 709 of this issue (2), provide detailed views into the structural organization of this large complex. These studies will pave the way for a more com- plete understanding of how gene expression is regulated.