Sigma Factor

By Levi Clancy for Student Reader on

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σ FactorSynonymOverview
σ 32RpoHHeat Shock σ Factor.
σ ERpoEExtracytoplasmic σ factor.
σ 54RpoNNitrogen responsive σ factor.
σ SRpoSStationary phase σ factor.

The σ factor is a prokaryotic initiation factor that binds RNAP and promotes attachment to DNA promoter sites in response to significant environmental changes. For example, specific σ factors respond to hot or cold environments. σ factors promote transcription of genes which are not transcribed under normal conditions; these genes encode proteins to aid survival of environmental stress. In technical terms, developmental responses involve transcription of genes encoding specialized σ factors. Region 1 regulates interaction with DNA. Region 2 binds RNAP and binds to the -10 promoter site. Region 4 binds to the -35 promoter site.