What does repressor mean?
A repressor is something that restrains or prevents a process from becoming active. Its most important scientific use is for a protein that regulates gene expression: it binds to DNA, or to another molecule involved in transcription, and blocks the production of RNA or protein. This makes repressors central to the way cells control which genes are active and when. The word can also be used more broadly for a person, policy, institution, or influence that holds back growth, speech, spending, or another activity. In general use, “repressor” tends to sound formal and somewhat abstract, whereas “inhibitor” or “suppressor” may be more natural in particular contexts. The term is especially associated with the lac repressor, whose role in bacterial gene regulation helped establish the basic principles of gene control.
A regulatory molecule, especially a protein, that inhibits gene expression by binding to DNA or interfering with transcription.
"The repressor prevented the gene from being transcribed."
This is the standard technical sense in molecular biology and genetics.
A person, thing, or influence that restrains or suppresses an activity, tendency, or development.
"The organization acted as a repressor of the proposed changes."
This broader figurative sense is formal and commonly used in social, political, and economic contexts.
Used for multiple regulatory molecules or for several people or influences that restrain or suppress something.
"These repressors control the expression of several genes."
The famous lac repressor helped researchers discover how cells switch genes on and off, making it one of the molecules that opened the modern era of gene regulation.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does repressor come from?
The word “repressor” was formed in English by adding the suffix “-or,” meaning “one who or that which does something,” to “repress.” “Repress” ultimately comes through French from Latin reprimere, meaning “press back” or “suppress,” from re- (“back” or “again”) and premere (“press”). Related English forms such as “suppressor” and “compressor” ultimately reflect the same Latin root of pressing.
Related word forms
How repressor is actually used
In biology, the term usually refers to a specific regulatory protein. In general or figurative use, it is broader and may sound formal or technical.
Easily confused with repressor
A repressor reduces or blocks a process, whereas an activator increases or stimulates it.
A repressor is commonly a specific regulatory molecule, while a suppressor is a broader term for anything that restrains or suppresses an activity.