SOS box is the

operator Operator may refer to: Mathematics * A symbol indicating a mathematical operation * Logical operator or logical connective in mathematical logic * Operator (mathematics), mapping that acts on elements of a space to produce elements of another sp ...

to which the

LexA The LexA repressor or LexA (Locus for X-ray sensitivity A) is a transcriptional repressor () that represses SOS response genes coding primarily for error-prone DNA polymerases, DNA repair enzymes and cell division inhibitors. LexA forms ''de fact ...

repressor In molecular genetics, a repressor is a DNA- or RNA-binding protein that inhibits the expression of one or more genes by binding to the operator or associated silencers. A DNA-binding repressor blocks the attachment of RNA polymerase to the ...

binds to repress the

transcription Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including: Genetics * Transcription (biology), the copying of DNA into RNA, often th ...

of SOS-induced proteins. SOS boxes are found near the promoter of various

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

s. LexA binds to an SOS box in the absence of

DNA damage DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is constantly modified ...

. In the presence of DNA damage the binding of

is inactivated by the

RecA RecA is a 38 kilodalton protein essential for the repair and maintenance of DNA in bacteria. Structural and functional homologs to RecA have been found in all kingdoms of life. RecA serves as an archetype for this class of homologous DNA repair p ...

activator. SOS boxes differ in DNA sequences and binding affinity towards

from organism to organism. Furthermore, SOS boxes may be present in a dual fashion, which indicates that more than one SOS box can be within the same promoter.

Examples

See

Nucleic acid nomenclature The nucleic acid notation currently in use was first formalized by the International Union of Pure and Applied Chemistry (IUPAC) in 1970. This universally accepted notation uses the Roman characters G, C, A, and T, to represent the four nucleotides ...

for an explanation of non-GATC nucleotide letters.

References

DNA repair {{genetics-stub

Examples

See also

References