The preinitiation complex (abbreviated PIC) is a complex of approximately 100 proteins that is necessary for the transcription of protein-coding genes in eukaryotes and archaea.  The preinitiation complex positions RNA polymerase II (Pol II) at gene transcription start sites, denatures the DNA, and positions the DNA in the RNA polymerase II active site for transcription.
The minimal PIC includes RNA polymerase II and six general transcription factors: TFA, TFB, TFD, TFE, TFF, and TFH. Additional regulatory complexes (such as the mediator coactivator and chromatin remodeling complexes) may also be components of the PIC.
Preinitiation complexes are also formed during RNA Polymerase I and RNA Polymerase III transcription.