Gene expression: surprises from the class III side.

Those genes which are transcribed by RNA polymerase III continue to give surprising results with respect to their cis-acting elements and transacting factors. As a result, a broader view of class III promoters has emerged and the internal promoters are not universal in classical polymerase III genes. The involvement of TFIID, TFIIA, a factor homologous to TFIIB and an RNA factor in class III gene transcription has further changed our thinking in regards to the mechanisms of transcription.