A long range goal of this laboratory is to be able to detail the events that occur during the initiation of transcription protein coding genes, transcribed by the RNA polymerase II machinery (also called class II genes), through a characterization of the proteins involved and their various protein:DNA and protein:protein interactions. The overall aim of this proposal is to continue and expand studies now in progress in my laboratory on the protein factors that operate through the initiator (Inr), a transcriptional control element proesent in all RNA polymerase II transcribed genes thus far examined. The emphasis of these studies is on elucidating the molecular mechanisms that modulate promoter reconition by RNA polymerase II, particularly in the context of non-TATA sequence containing promoters. While it was though initially that most of the RNA polymerase II transcribed genes contained a TATA motif, it is now clear that many genes do not. An alternate control element capable of directing transcription complex formation has not yet been described for TATA-less promoters; however, recent experiments have indicated that the Inr is capable of directing the formation of a transcription competent complex. Thus far, studies on the specific transcription of class II genes have indicated that most of the enzymatic complexity as well as the regulation of RNA synthesis catalyzed by the RNA polymerase II transcription machinery probably resides in the initiation step - the recognition of promoter sequences. Protein fractions have been isolated that when mixed together have reconstituted specific transcription activity from many class II promoters. Most of the emphasis to date has focused on t;he isolation of regulatory factors for specific genes. In many instances the genes encoding these particular DNA binding proteins have been cloned. However, a description of the exact mechanism of action of these regulatory proteins will not be possible until the mechanisms of action of the general transcription factors are understood. Our studies on promoter recognition and activation by the general transcription factors of the RNA polymerase II transcription system, including TATA-less promoters, have broad implications for the mechanism of RNA synthesis in general and will provide the basis for understanding how specific gene transcription factors can modify the transcriptional activiyty of a particular gene or a set of genes. It is likely that these studies will yield basic principles from which the regulatory mechanisms of class II gene expression can be discerned at the molecular level.
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