SOS box is the operator to which the LexA repressor binds to repress the transcription of SOS-induced proteins.
SOS boxes are found near the promoter of various genes.
[1] LexA binds to an SOS box in the absence of DNA damage.
In the presence of DNA damage the binding of LexA is inactivated by the RecA activator.
[3] See Nucleic acid nomenclature for an explanation of non-GATC nucleotide letters.