This minireview provides an updated alignment and analysis of the σ70 family of proteins, focusing on their sequence conservation, structure, function, and evolutionary relationships. The σ70 family is divided into three groups: primary sigma factors (Group 1), closely related but nonessential sigmas (Group 2), and alternative sigmas responsible for specific regulons (Group 3). The review highlights four highly conserved regions within the σ70 family, with Region 2 being the most conserved and involved in core binding, promoter recognition, and DNA strand melting. Region 3 may also contribute to core binding in some sigmas, while Region 4 is crucial for recognizing the -35 promoter sequence. The N-terminal portion of the protein aligns with the -35 region, and a more N-terminal portion aligns with the -10 region. The review also discusses the structural relationships of σ70 family members to other sigma factors and bacteriophage sigmas, noting that bacteriophage sigmas are only weakly related to the σ70 family. Overall, the σ70 family appears to be well-conserved in structure and function, with different groups of proteins serving distinct roles in transcription regulation.This minireview provides an updated alignment and analysis of the σ70 family of proteins, focusing on their sequence conservation, structure, function, and evolutionary relationships. The σ70 family is divided into three groups: primary sigma factors (Group 1), closely related but nonessential sigmas (Group 2), and alternative sigmas responsible for specific regulons (Group 3). The review highlights four highly conserved regions within the σ70 family, with Region 2 being the most conserved and involved in core binding, promoter recognition, and DNA strand melting. Region 3 may also contribute to core binding in some sigmas, while Region 4 is crucial for recognizing the -35 promoter sequence. The N-terminal portion of the protein aligns with the -35 region, and a more N-terminal portion aligns with the -10 region. The review also discusses the structural relationships of σ70 family members to other sigma factors and bacteriophage sigmas, noting that bacteriophage sigmas are only weakly related to the σ70 family. Overall, the σ70 family appears to be well-conserved in structure and function, with different groups of proteins serving distinct roles in transcription regulation.