Alternative sigma subunits of E. Coli.

Alternative sigma subunits lead to distinct conformational changes in RNA polymerase holoenzyme & to recognition of corresponding consensus sequences ; are weight dependent .

Sigma subunit 28: Molecular weight = 28kD, Consensus sequence ( -35 = TAAA, -10 = GCCGATAA), Flagellar synthesis & chemotaxis

Sigma subunit 32: Molecular weight = 32 kD, Consensus sequence (-35 =CTTGAA, -10 = CCCCATTA), Heat Shock genes

Sigma subunit 54: Molecular weight = 54, Consensus sequence (-35 = CTGGP) (-35 =. CTTGPyAPyPu, -10 = TTGCA), Nitrogen Metabolism

Sigma subunit 70: Molecular weight = 70, Consensus sequence ( -35 = TTGACA, -10 = TATAAT); Housekeeping genes (VERY important subunit which allows for transcription!)