A sigma factor is a protein that binds to RNA polymerase and directs it to specific promoters on DNA during the process of transcription. By helping RNA polymerase locate the right starting point for transcription, sigma factors play a crucial role in regulating gene expression and ensuring that genes are transcribed at the appropriate times and levels. They are vital for the initiation phase of transcription in prokaryotes, influencing how cells respond to various environmental signals.
congrats on reading the definition of sigma factor. now let's actually learn it.