HIV-infected T cell FLICKR, NIAID HIV leads to AIDS primarily because the virus destroys essential immune cells called CD4 T cells, but precisely how these cells are killed has not been clear. Two papers published simultaneously today (December 19) in Nature and Science reveal the molecular mechanisms that cause the death of most CD4 T cells in lymphoid tissues, the main reservoir for such cells, during infection.
Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors. Transcription factors can bind to specific DNA sequences called enhancer and promoter sequences in order to recruit RNA polymerase to an appropriate transcription site. Together, the transcription factors and RNA polymerase form a complex called the transcription initiation complex.
RNA polymerase and accessory proteins (transcription factors) bind to the promoter to initiate production of an mRNA transcript. Interactions of proteins at the promoter regulate gene actvity by activating or repressing transcription.NA polymerase and accessory proteins (transcription factors) bind to the promoter to initiate production of an mRNA transcript. Interactions of proteins at the promoter regulate gene actvity by activating or repressing transcription.