Regulatory Sequences Control Gene Expression

Enhancer and Silencer Elements

Role of 3' Sequences

Role of Introns

Conserved Sequences in Eukaryotic Promoters

Trans-Acting Factors Control Gene Expression

Cloning A Plant Trans-Acting Factor

Regulatory Genes As Trans-Acting Factors

Tissue-Specific Binding Of Trans-Acting Factors

Course Topics

Main Page

Conserved Sequences In Eukaryotic Promoters

We have seen that promoter regions are essential for gene expression. If a particular gene is to be expressed, then RNA Polymerase must bind to the promoter. We have already discussed several types of promoter sequences which play different roles in expression. These sequences can be grouped into two different classes. Those sequences which are found in nearly all promoters and those which seem to associated with either temporal or spatial regulation.

Conserved Modules Sequence Possible roles
TATA Box TATAAA define transcription start site
CAAT Box GGCCAATCT define RNA Polymerase binding site
GC Box GGGCGG define RNA Polymerase binding site

We have not discussed the GC Box yet. The conserved sequence is GGGCGG and is usually found in multiple copies in the promoter. Each of these conserved sequences in the table must be important otherwise they would not be conserved. In mammalian systems mutations in the CAAT and GC boxes have a larger effect on transcription than mutations in the TATA box. But none of these sequences are universally required because genes have been sequenced that do not one or more of these sequence modules. To date, not enough information has been gathered about plant promoters to define the relative importance of any one module.

Copyright © 1998. Phillip McClean