Medical Dictionary

sigma factor

noun sig·ma factor \ˈsig-mə-\

Medical Definition of SIGMA FACTOR

:  a detachable polypeptide subunit of RNA polymerase that facilitates the initiation of transcription by recognizing specific DNA promoter sites

Browse

How to use a word that (literally) drives some people nuts.
Test your vocab with our fun, fast game
Ailurophobia, and 9 other unusual fears