attenuator

at·ten·u·a·tor

(ă-ten'yū-ā-tŏr, -tōr),

1. An electrical system of resistors and capacitors used to reduce the strength of electrical signals, as in ultrasonography.

2. The terminator sequence in DNA at which attenuation occurs; located between the operator and the gene for the first protein in an operon.

attenuator

a regulatory NUCLEOTIDE sequence occurring in the LEADER REGION of an operon (see OPERON MODEL and containing a TRANSCRIPTION stop signal. The attenuator acts as a fine control mechanism for the activity of structural genes, sometimes being operative, sometimes not, depending on conditions in the cell.