RNA polymerases I or III do not have a CTD so no capping is stimulated

TLS Online TPP Program

#Id: 6145

#Unit 3. Fundamental Processes

Cockayne syndrome can be caused by mutations in either of two genes (CSA and CSB), both of whose products appear to be part of or bound to TFIIH, and can also be caused by specific mutations in XPB or XPD.

TLS Online TPP Program

#Id: 6146

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6147

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6148

#Unit 3. Fundamental Processes

TLS Online TPP Program

#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.

TLS Online TPP Program

#Id: 6150

#Unit 3. Fundamental Processes

H2AX phosphorylated at serine 129 in yeast, 139 in mammals) is referred to as g-H2AX. g-H2AX is a universal marker for double strand breaks