Introduction The Transcription Complex Basic Cis-acting Sequences Enhancers and Silencers Methylation Trans-acting Factors Signaling Control of Transcription Hormonal Control of Gene Expression Signal Transduction Pathways Study Questions Control of Gene Expression in Eukaryotes WWW Links Genetic Topics

Basic Cis-acting Sequences The sequences just 5' of the start site of transcription are the most important for the initiation of transcription. This is where the transcription complex is built. In general, this region is called the promoter. For eukaryotes, several sequences same to be conserved among many genes. One such sequences is the TATA box. The sequence is located about 30 bases upstream (-30) from the transcription start site and is the one sequence required for any significant transcription to occur. Other sequences add in transcription but are not always part of promoter. The two most found are the CCAAT box (called the CAT box) and the GC box. Because mutants of these three sequences only express mRNAs at low levels, these are considered the most important sequences of the basic transcription complex. Copyright © 1997. Phillip McClean