The promoter of the araBAD operon from E. coli is activated in the presence of arabinose and the absence of glucose and directs expression of genes encoding enzymes required for arabinose metabolism. 

Unlike the cases of lac and gal genes, where a repressor and an activator work together, here two activators work together: AraC and CAP. 

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#Id: 1687

#Unit 4. Cell Communication and Cell Signaling

Recombination between the VH and D-JH segments follows during the pro-B-cell stage.

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#Unit 4. Cell Communication and Cell Signaling

VpreB and λ5 (called a surrogate light chain), to form a pre-B-cell receptor.

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#Id: 1689

#Unit 4. Cell Communication and Cell Signaling

Light-chain recombination occurs at the small pre-B-cell stage of B-cell development.

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#Unit 4. Cell Communication and Cell Signaling

Site of DNA cleavage- Recombination Signal Sequence (RSS) 

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#Id: 1691

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 1692

#Unit 4. Cell Communication and Cell Signaling

Recognition of Recombination Signal Sequence (RSS) by the RAG1/RAG2 enzyme complex.