PI-3 kinase was first identified in studies of the 

polyoma virus, a DNA virus

TLS Online TPP Program

#Id: 7501

#Unit 4. Cell Communication and Cell Signaling

Site of DNA cleavage - Recombination Signal Sequence (RSS) 

TLS Online TPP Program

#Id: 7502

#Unit 4. Cell Communication and Cell Signaling

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

TLS Online TPP Program

#Id: 7503

#Unit 4. Cell Communication and Cell Signaling

RAG1 is expressed at all phases of the cell cycle, RAG2 is stable only in G0- or G1-phase cells.

TLS Online TPP Program

#Id: 7504

#Unit 4. Cell Communication and Cell Signaling

Threonine residue T490 on RAG2 is phosphorylated during the S, G2, and M phases of the cell cycle, and this phosphorylation triggers the destruction of RAG2. 

TLS Online TPP Program

#Id: 7505

#Unit 4. Cell Communication and Cell Signaling

RAG1 is the predominant recombinase; it forms a complex with the RSS that is stabilized by the binding of RAG2. RAG2 by itself does not exhibit detectable RSS binding activity

TLS Online TPP Program

#Id: 7506

#Unit 4. Cell Communication and Cell Signaling

RAG1 subunit and contains two aspartic acid residues and one glutamic acid residue (D600, D708, and E962, respectively). This active site “DDE motif” is found in many enzymes that cleave DNA