P nucleotide addition results when the DNA hairpin at the coding joint is cleaved asymmetrically.

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#Id: 8927

#Unit 2. Cellular Organization

ATM and DNA-PK are specifically activated by double-strand breaks

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#Id: 3642

#Unit 3. Fundamental Processes

The Class I enzymes share two homologous polypeptide segments that are components of a dinucleotide-binding fold (Rossmann fold, which is also present in many NAD+- and ATP-binding proteins.

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#Id: 6149

#Unit 3. Fundamental Processes

Ku70, Ku80, DNA-PKcs, Artemis, XRCC4, Cernunnos-XLF, and DNA ligase IV. Ku70 and Ku80 are the most fundamental components of NHEJ. 

They constitute a heterodimer that binds to the DNA ends and recruits DNA-PKcs, which is a protein kinase. DNA-PKcs, in turn, forms a complex with Artemis. Artemis is both a 5’-to-3’ exonuclease and a latent endonuclease that is activated by phosphorylation by DNA-PKcs. 

These nucleolytic activities process the broken ends and prepare them for ligation. Ligase IV performs ligation in a complex with XRCC4 and Cernunnos-XLF.

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#Id: 9605

#Unit 4. Cell Communication and Cell Signaling

The cytosolic domain of RTKs contains an intrinsic protein tyrosine kinase domain.

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#Id: 7365

#Unit 5. Developmental Biology

Drosophila eggs undergo Superficial cleavage.